Mushroom Grows on Chiikawa is exactly as it looks: Chiikawa infested with a mushroom.

One day, suddenly, a large mushroom grew on Chiikawa's head. Fortunately, Hachiware scraped it off from the base with a stone, safely removing the mushroom.

However, the mushroom was not completely removed. It had grown quite large, and Chiikawa's consciousness was beginning to be overtaken. Reflecting on his inadequate response, Hachiware strove to remove it completely this time, saying “I'll go to the limit this time!” and fervently scraped the base with the stone.

Afterwards (though Chiikawa's head got a bit dented), they successfully removed the mushroom. The two ate the mushroom together, with Chiikawa showing a somewhat complicated expression.

Later, a parasitic mushroom also grew on the head of a flying squirrel, but its fate is unknown.