Leviatán, 1

When a rescue team enters the Leviathan - a ship that has been drifting through space for years - they find the tattered diary of a young man named Kazuma, in which he relates that, somewhere on the ship, there is still There is a survivor of the catastrophe that took place inside. Upon reading it, the team members discover that, years ago, on a school trip to Earth, Kazuma and his classmates had been trapped on the ship after an explosion in the hull. Together with his friend Futaba, Kazuma eavesdrops on a conversation from the professor in which he confesses that there is not enough oxygen for everyone and that the only hope for survival is the cryogenic chamber at the heart of the ship. However, it can only house one survivor, so a bloody fight begins to hide this secret from the rest of the people on the ship.