User blog comment:Vulture Droid/Perverted Trio and Aika/@comment-26709288-20180527045035

The problem is they don't really play any role in moving the story along even Issei's parents played a role in the story and they don't have pages. They don't fight, they don't have any history or anything really pertaining to mythology or lore. Even Aika Kiryuu later learning about devils isn't that interesting.