Complex sentence: That event forced Takumi to renounce fighting, later seeing the spirit of Kusaka who manipulates him to revive him, but Haruto and Keisuke manage to convince Takumi to move on from his survival guilt, causing Kusaka's spirit to dissappear.
Split into simpler sentences: That event forced Takumi to renounce fighting, later seeing the spirit of Kusaka who manipulates him to revive him. But Haruto and Keisuke managed to convinced Takumi to move on from his survival guilt, causing Kusaka's spirit to dissappear.