Review of World Trigger

The series started off great, but after the Large-Scale Invasion Arc, it went downhill. The world(s) building was great and had potential, but after the Invasion arc they focused on some pool and beach episodes, and Ranking Wars. During the Ranking Wars, there was explanations on strategies from each team before, during, and after the matches with use a small amount of focus on the actual fights. Also, filler or not, after the Invasion arc, the Border agents fought off against a horde of enemies, with some top level enemies mixed in. Most of the high ranking agents did well againstthe large scale invasion, but during a filler arc, some of the same rankers had problems with only one not so OP enemy.
Not sure why Osamu was the MC, he would fit better as a side character. I liked his courage, but he was weak and the only reason why he survives is because of others. Yet, he wants to go behind enemy lines. He only gets slightly stronger, and they want to make him out to be some kind of genius, but he is just an above average strategist. Then there is the freaky big headed Chika, some of her decisions make me wonder what is the point of that big head of hers, especially during the filler arc. The rest of the characters are pretty decent, Jin and Kuga should be the main characters of the show.