Soldiers in space! That sounds like it would make a good shounen manga.

[From his voice, it's hard to tell if he's serious or mocking; in truth, it's probably both. The occasional falling coconut gets an unhurried look from Izaya, just in case the sound is caused by something else. When one hits particularly close, he wanders off to pick it up.

Giant floating jellyfish?] That depends on how venomous they are, I presume.