The MC travels to the Interstellar/ABO era, where he becomes ML's best friend and Vice Commander. I'm not sure, but the MC transmigrated to several worlds, and the ABO is the novel's first arc. The protagonist of that world is an omega who disguises himself as a beta and is always close to the ML. MC is a cold and strict vice commander. Because of the protagonists' pheromones, all of the alpha I battleships are affected, and the MC orders them to be knocked out. Because he is the vice commander and the ML is unconscious, he is responsible for everything. Before he sacrifices himself to the wormhole. He plays the piano before sacrificing himself to the wormhole, and everyone sees him because it's a live broadcast? I recall that at the very end, the ML had the MC's name plate, which he treasured. I recall that the novel's second arc is about a demon snake? In this scene, the MC sacrifices himself to serve as the boundary between the mortal and demon world.