Stop!! Hibari-kun! S01 E30 Beware of Phantom Thief Mouse Kid!!

Hibari and Seiji meet Kaneda Kanesuke, the brother of Kōsaku's mother, Harue. Ibari is outraged on his behalf that his uncle is a no good thief and scares him off. He then falls off the roof trying to escape Hibari's proposal of marriage.