It's a Sketching Contest! Dokuro-chan!, It’s a Bubble and Scrubbing Battle! Dokuro-chan!

Sakura, Dokuro and Shizuki are on a school trip where they are asked to draw the scenery, but not without Dokuro. After Dokuro and Zakuro are scared of a "monster" they read about in a myth book, they then want (and force) Sakura to join them in the bath.