Yuki Yoshida ( Nick Name : Tomonori, Maelstrom) Maelstrom, A Vampire Ninja of a faction from the opposed of Sera , Same High School as Ayumu , Not same Class ( Known as Tomonori because her name kanji ) First time introduced at episode 7 of Koreha when Ayumu was defeated by megalo And she come to help using a tonkotsu ramen soup to defeat megalo.( Really weird don't you think , using a ramen to defeat a monster)