Gaap is perhaps the first boss who can fly and thus being a huge pain.
I tried Judas + all 3 girls, but all 5 attempts failed because Gaap moved to my spellcasters and killed them.
Kyle is perhaps the better choice due to his forth Ougi Shinkuu Rensatsuken. It is a pretty long attack that will interrupt Gaap from doing anything and it also lift Kyle to midair and will still continue to attack Gaap.
While your girls are casting Tier 3 Spells (Fearful Storm is the best one), Kyle will attack Gaap between two spells to keep him busy.
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