Complex sentence: Amagiri Ayato, a Starpulse Generation arrived at Rikka at the invitation of the Student Council President of the Seidoukan Academy, Claudia, and right after that he incurred the wrath of the "Petalblaze Witch" Julis, and ended up having to duel her.
Split into simpler sentences: Amagiri Ayato, a Starpulse Generation, arrived at Rikka at the behest of the Student Council President of Seidoukan Academy, Claudia. During his time at Rikka, he incurrs the wrath of the "Petalblaze Witch" Julis, and ends up having to duel her.