Sea Monster Mission! [C-rank, solo, p, nk]

Kozai wasn't hiding this time. He was actually preparing tea when the mission package came. The tea was one that he had added cinnamon to, not as a challenge (whatever that meant), but as a test to see what kind of flavor he could get out of it. As always, it went without saying that he loved the more comforting tastes rather than the really weird exotic ones. The package dropping by bird via his window (how did the bird carry that thing, anyway? It must work out or something) startled him slightly, almost causing him to drop his cup, a couple of drops of tea spilling onto his hand. Sucking in his breath at the slight prickling of the heat, he cleaned up and took up the package, inspecting it before opening it.
It was another mission, of course, and again, it was something to do with a non human threat. Then again... could this really be classified as an animal mission? More appropriately, was it even a C rank mission to begin with? Hmm... they must have messed up, or something. He heard the footsteps of that random girl outside coming to knock on his door obnoxiously for the fourth time that day, and decided to book it out the window, using his chains and dampening seals to reach the ground safely. Luckily, no one but a drunkard saw him.
He made his way out to the lake where the monster was supposed to have been. Sitting down, he brought his knees in close to his chest and huddled there, as the banana he had just threw into the lake bobbed.... and then, with a loud splash, vanished. Whoa, what was that! He slowly stood up, as the water began to bubble and roil like mad. What was this...?
A large tentacle came crashing down on the pier. Shit, he had no choice.
He leaped backwards, bare feet getting wet as the water displacement fully came into effect now. As he landed, he placed a Lunar seal on the rock behind him, not activating it yet. He was still not really confident in how it worked, and was somewhat nervous about using it. So, if possible, he would have to avoid doing so. Then again, it was becoming more and more difficult as another tentacle came whizzing toward him, this time from his right. This thing was enormous! And just how many tentacles did it have? He ducked, but then had to roll as another one came down, attempting to crush him once again. He could see how this was a complaint for fishermen. Also, it was really terrifying...
But it's not human, he thought. Which means I can take it without being afraid.
And indeed, he could. With a buzz, the lightning chakra of the Hell Stab surrounded his hand, and as then next tentacle came for him, he lift his arm and severed it, sending it crashing down next to him. With a roar of pain, the beast arose from the water.
Holy fuck, just how many tentacles did it have? Well, as he could now see it... he could lock it with his chains. So, he tried to do so. However, the beast seemed stronger than he, and began to drag him into the water.
Last resort time.
Activating the lunar seal behind him, he felt his perspective turning as "down" became the direction that the seal was in. He fell, and as he did so, the beast was dragged with him... and with a terrible ripping sound, it came out...? It was a plant? Oh well, that was fine. Mission complete.