Toilet-bound Hanako-kun, Vol. 4

Nene steps into the spotlight! The mermaid kingdom hasn't forgotten her,
and they're back to claim what's theirs! Can Hanako protect her from becoming
permanently fishy? Meanwhile, Kou makes friends with an odd ghost haunting the
entrance to the middle school division. Kou has no idea who this guy was when he
was alive, but that doesn't mean he can't help him solve his unfinished
business! Will the junior exorcist be able to help this friendly ghost pass
on...?