Who Came Up With the Onomatopoeia "Kapo~n"? It's Amazing

With summer vacation coming to an end, Nagi is saddened that there won't be anymore free time to spend with Hayate. After reading a manga, Nagi decides to take Hayate fishing. While Hayate and Nagi are having a romantic time fishing (in Nagi's mind), the lord of the lake overturns their boat. Returning home, Hayate takes a bath and is joined by Tama who breaks the bath's water heater. Hayate becomes depressed because he believes he's always causing problems for Maria and attempts to fix the bath, only for it to be destroyed once again by Tama.