Despite its ridiculous title, this was a really fun book. Hanako-kun is one of the seven mysteries of Yashiro’s school. She summons Hanako-kun one day because she’s heard she can be granted one wish, but Hanako is nothing like she expected. To begin with, he’s a boy bound to a toilet in the girls' bathroom! Yashiro is desperate to be part of a couple, so she eats a mermaid scale and tries to give its matching scale to a boy she has a crush on (as legend says he will be inexplicably bound to her forever), but she chickens out at the last minute. The scale turns her into a fish, but Hanako eats the matching scale to save her from a worse fate, and fights off the mermaid who has come to claim Yashiro. From that point on, Hanako and Yashiro and bound together with a supernatural bond. Yashiro becomes Hanako’s assistant and the two continue to explore the supernatural elements of the school, keeping them from harming the mortal students whenever possible.

Alex continues her search for her sister, and only a select few people can remember her.  She gets help from a few other students who decide to recreate the gate spell, but this will be painstaking and take a lot of effort.  Meanwhile, Teacher ferrets out the one who betrayed the hunters, and he moves his group into a safe house with Mr. Roi, the eccentric teacher who has also been giving extra lessons to Alex.  We also learn about Nereshai, an ancient race of extremely powerful magic users, and the Sohrem, a group of powerful magical beings who have begun searching for new hosts within the school building.  Centuries ago, the Nereshai sealed the Sohrem, but that seal has been broken, and it's up to the students and teachers to put everything right and bring home those who have been forgotten.