[Incest, Kraken TF]

"Umi, you can't! You just can't!"

The boy's tears fell to the ground, all while he hugged his older sister's thigh as tightly as he possibly could. He didn't want to let her go. He didn't want to see somebody close to him disappear again. Not after what had happened the last time...

"It's okay, Riku." His older sister, a blue-haired girl by the name of Umi, carefully kneeled down as she pried his hands off her thigh. All while carefully patting him on the head. "I won't get hurt. I'll be with the Order. They managed to strike back at the Monster Girls that had conquered the area where Mom disappeared. It won't happen to me. I promise."

The two of them had lived together for what felt like forever. At least, Riku could remember how it felt to be cared for by his Mom and his Sister. But when he reached five years of age, his Mom disappeared. And all of the duties involving parenting fell on Umi. A role that she had taken to as naturally as he had avoided going into the sea because of what they knew...

But he didn't want her to go. Even as she tried to sound as confident and as supporting as she could be, the tears still rolled down his cheeks. "But what if you do sink? What if you end up just like Mom? I don't want to lose you, Umi! I don't want to be all alone!" You really couldn't argue with him when he was in this state...

Umi sighed, and hugged the boy as much as she could. Slowly snuggling him as she rubbed the back of his head. "You know I have to, Riku. If I don't, we won't be able to stay like this. We're running out of money, and we're in danger if there's ever going to be another invasion from the water... I have to help them. Once the town is safe, and the waters leading out to sea are clear... Then I'll come home, and we'll be together until the day we grow old. I promise. But you have to trust me. And you have to realize I have to do this..."

"I don't... I don't want to see you go..." He was still a child, after all. Only just reached the age of 12, and he was forced to watch his sister tell him that she had to go. It was not fair. It was not right. But in the depths of his childish heart, he understood. All while looking into her eyes as the tears just kept streaming down. "You... You swear, right? You'll come home?"

"Promise." Umi said, kissing the young boy right on his forehead. "I'll do more than that. I'll bring Mom home too. Even if she's been turned, I'll make sure that she'll be back to normal. So she can understand what we've had to deal with ever since she disappeared."

"B-But... B-But she can turn you too, if she's..." Riku didn't feel any sort of comfort from that promise, not until a finger made its way onto his lips and quieted him down. He looked into his sister's eyes, and he saw the confidence brimming within. "You... You really think you can bring her back, Umi..?"

"I told you. I'll bring her back. Even if it means I'll end up just like her." She said, giving the young boy another hug. "I'll make sure I'll remain the same Umi you've come to love. Alright, Riku? Stay strong for me, and always believe in me. That way, I'll be home faster than you think."

Riku sniffled and wiped his eyes on her shoulder, before nodding the best she could. "I... I'll believe in you, Umi. So you better... Y-You better bring her back! And you better not get turned or anything! I don't want to see you as anything but my Umi!" His childish side popped forth in all of its glory. The kind of childish behavior that demanded everything be like he wanted it. Even if it was impossible. Because he knew that she would do everything in power to make it right, like she had done so many times before..

"Of course, Admiral!" Umi giggled, teasing her dear brother by letting go of him and saluting like she was another common marine in the navy. "I promise you, Riku. We'll be back before you know it. Just remember to think about us, and we'll be back to be with you. We'll be back to protect you, and make sure that you grow up to be big and strong."

Riku nodded and saluted back. Even if he didn't really get what the salute was supposed to mean, he wanted to show that he trusted her. And just like that, with a single laugh more from both of them...

She left. And she never came back...

---

It had been a year since that day. It had been a year since he put his trust in her. What was he doing, thinking that she really could live up to everything that she had told him? They were all just empty words, and he knew it even back then. He knew that she wouldn't be able to live up to what she had told him.

Because it barely took a week before he heard about the ship that she was supposed to be aboard... How it immediately had been forced to sink thanks to an assault by the Monster Girls that had been forced from the depths. And with the ship falling to pieces, there was no way that she hadn't drowned. No matter how hard he prayed, no matter how hard he believed in her, she didn't return. Not the day after that, not the week after, not the month after. He had so much hope in his heart, and it was squandered as she proved that she couldn't live up to what she had promised. Thoroughly making his heart ache...

It was why Riku was currently down at the beach that sat at the edge of town. It was why he was currently pushing a boat out to the very edge. Because even though he had lost hope, he didn't want to disappoint her like she had disappointed him. So he had done something every month. Something that had built his strength, and something that would serve as a testament to the sister he had lost.

The boat he was pushing was one that he had made. Every month, over the last year, he had pushed a boat down to this shoreline. And he had pushed it out to sea, in a vain hope that one would reach his sister. Of course it couldn't reach Umi, she had been pulled under the surface of the water thanks to the fact that she was a natural enemy of the Monster Girls. And if she had survived... There was no chance that the Order would let her live. In the time that had passed since he allowed her to leave, he had learned about the wicked things that the Order did to try and make it seem like they were winning. They were liars. Liars all of them...

"Umi... Please..." Riku muttered, before letting out a yelp as he managed to nearly twist his ankle due to the uneven nature of the sand underneath. Thankfully, the boat was there to stop him. But it just ended up sliding down further as he fell, letting it sink into the water before he had a chance to properly pray for her.

The sight of it drifting away like that... It was like how his hopes had drifted from his heart. He just closed his eyes, and looked up at the night sky. He couldn't even manage to pay respects to her in the right way. So he was not any better than her. He lied in regards to her promise. Losing hope and not believing in her any more. So in that sense, they were more like one another than he might've thought...

A sad laugh left Riku's lips, as he let his body rest on the sand...

Right before a loud splash echoed from the surface of the water, causing Riku to jolt up from the ground as he looked towards the water. What in the world was happening, were they being attacked? W-What was going on, he wasn't prepared for anything like this! U-Umi, he needed... N-no, she wasn't here, he had to fight on his own to protect the town..!

As Riku clenched his fists, he looked past the water that rained down, and his stance immediately lost all tension. Because he didn't believe what he was looking at. There's no way that the girl who had just risen from the depths was the girl that he had been believing in...

"Aaaahhhh...! Took me long enough to find my way back here!" And yet the cheery tone that left the girl's lips made it hard to disprove. Even if she was a lot older looking, even if she was a Monster Girl with tentacles that looked like they could creep into any little hole on his body... She was still Umi. There was no mistaking it.

Riku blinked as he slowly walked towards the girl in the water. "U-...Umi..?" He muttered, not at all able to believe what he was seeing. She had turned into a... Kraken..? At least, that's what he thought she was. It fit the description of the squid-like Monster Girls that he had read about when he tried to flip through his Mom's old notes...

The Kraken, which was about two and a half times his size, smiled from ear to ear as she heard that familiar voice. "Riku! There you are!" She paused, before laughing as wickedly as possible and tipped her head slightly, as to make her hair hide away her eyes. "There you are, my prey I've been hunting for you for so long, and here's the shore that you were waiting on..."

"...That's the worst impression of a Monster Girl that I've ever heard." Riku couldn't believe it. Not only had she come back, but she was still the very same Umi as ever. Because her impressions were so terrible that they evoked nothing but shame in the ones that heard it.

Umi laughed as she lifted her head up again, before shooting her tentacles towards Riku. Tentacles that very quickly grabbed him and pulled him into the water, until he was pinned right against her body. "You saw right through me! But you're also here way too early, I thought you'd be here in an hour or so! Come on, you just had to ruin my grand plan to return to you and make you feel all sorts of happy!"

"I would've been scared to death if I saw you acting like that and didn't see you pop out of the water in the first place!" Riku shouted, before the tears ran down his cheeks. He couldn't stop it. He had missed her so much. "I thought you had drowned and died, Umi! I thought you had left me all alone after lying to me! Why'd you come back now, it's not like this place is that far away from the Order's headquarters!"

Umi looked at her brother, watching the tears slowly stroll down his cheeks yet again, before softly smiling. "I had to fight against Mom. And it took a really long time. You wouldn't believe what he did to try and make me submit. Then again, it's not like she hadn't suffered all that time either. She just externalized it by becoming a bigger Kraken than me, and then tried to take it out on everyone that served her."

"But it's because you believed in me." Umi said, as she brought him closer to her face, while his head could rest up against her rather generously and excessively matured bosom. "It's because you were always sending out your help to me. That's how I beat her. Of course, then I find out that you've been sending boats and I could've just... Well, swum back up to the surface and tried to paddle back to the town, but I was too busy trying to fix her, and-"

Riku just stared at her, the tears still in his eyes. "You... You beat Mom..? Is... Is she okay?" Hearing her like this, hearing what she had done... It brought him relief but it also served to confuse him.

"Well, she's still giant. But she's recovering. And she told me that I could do whatever I wanted to do. As long as I didn't cause trouble for people, because then I'd be no better than she was." Umi explained, before winking. "So that's why I came back. And that's why..."

Riku felt a sharp sensation rush through him, before he felt cold for a few seconds. Right before he was pushed further against Umi's almost slimy body, the warmth that radiated off her poured into him and made him feel a lot more comfortable. Even if he was feeling really weird at the same time. "U-Umi..?"

"Aaahh... Riku, you don't know how long I've been waiting to do something like this... How long I've watched you grow up, how long I've been harboring this kind of love..." Umi panted and gasped, her cheeks flushing red the longer she rubbed her younger brother up against her. It felt so good to have him close to her. Especially as she sank down into the water, letting the mixture of the cold sea and her warm body overwhelm her...

He was dragged down as well, preventing him from seeing the tentacles grabbing onto his clothes and ripping them apart, letting him be just as naked as her. And as soon as he felt the proper contact of his naked body pressing against hers, he couldn't stop something from growing nice and hard down below the belt, the act itself drawing a massive blush onto his cheeks.

"U-Umi, w-we-" He didn't get to finish, because he was suddenly stopped by her lips meeting his. Riku couldn't stop his sister from sinking further below the surface of the water, letting him barely stay above until they were at the same level. He couldn't see a thing, but he could definitely feel something happening below. A sensation that made him tremble and pant, the sheer pleasure rushing through making him writhe.

He could look straight into her loving eyes, but he couldn't keep his focus on them. It felt too good. It just felt too good. Whatever she was doing to him was overwhelming him. Whether it was the warmth from her body, or the warmth from her lips, or the love that he felt pouring through her, or all of the above at the same time... He just didn't expect that his sister would go this far, just to make him feel good. But he also didn't want her to stop.

Umi didn't want him to stop. He could tell that just from looking at her. From the way that she snuck her tongue into his mouth. From the way that her breasts squeezed around his shaft. All of it just melted together and made him feel so good. It was... It was..!

"A-Aahh!" Riku cried out as he suddenly shoved his hips forward while rearing his head back, forcing his sister to stop kissing him in the process as he released the contents of one of his very first orgasms right into her bosom. Splattering his cum all over her, only for it to be diluted by the water around it...

Umi smiled. Not just because she had finally made him cum, like she had always wanted to, but because he had actually managed to cum a lot. Much more than she originally would've expected. But she wasn't done. She wasn't just going to make him cum once with her breasts. She wanted much more...

"Sit still, Riku..." She said, as she lifted herself out of the water ever slightly. Raising her breasts until they were at the same level as him, pushing him into them in the process, before sinking down...

Riku's eyes widened as he felt something tight and wet squeeze down on him. Something that made him cry out louder and louder with every passing second, as it felt like it just kept squeezing more and more. He liked it, but he couldn't handle it. So even though he had been forced to orgasm just mere moments ago, he couldn't stop himself..!

"Umiiii!" He cried out as he came yet again. His cum poured right into her, letting it all soak its way into her womb. All while he desperately tried to grasp onto her and squeeze tight, in an attempt to keep himself from passing out...

And once his orgasm finished, he collapsed. All while those loving tentacles wrapped around him and caressed him, the young boy panting after having inseminated his older sister. He was beyond exhausted. He was beyond overwhelmed... But he was not dissatisfied. He... He loved it. And he loved her.

"There there. There there..." Umi slowly whispered into her dear younger brother's ear, all while he rested against her body and quietly pressed against her breasts. "You did very well, Riku. You kept it all up like I asked you to... You kept believing. Even when it seemed like I had disappeared... You really proved your love to me, so this is just one way I'll be paying you back..."

Riku slowly tried to look up at her, trembling a bit as he was still exhausted. "O-One way..?" He muttered, panting despite how nice it felt. Right now, he just wanted to fall asleep inside her... Inside of this water, so he could be with her...

"Well, we need to make sure that we make Mom proud and keep the family going, don't we?" Umi said, gently putting her hands in between the boy's body and her belly. All while winking.

Riku blinked. And then he just smiled and closed his eyes. Yeah, that was too much for him. Knowing that he knocked her up... That was far too much.

"Ehehe... Sleep tight, Riku. We have a lot to catch up on..." His older sister whispered, as she let her little lover rest...