Chapter 021 is twenty-first chapter of Volume 4.
Ami invites Nanami to go to the beach with her and Kei but Nanami was too depressed from rejection. Nanami refused to eat her food, making Tomoe come. He attempted to force her to eat a shiitake but remembers his promise not to touch her and leaves. Ami repeats her invitation to Nanami, who finally accepts to take her mind off Tomoe. When Tomoe finds out, he doesn't allow her to go. Firstly, it was dangerous, secondly, Tomoe could not go into the water and protect her. Mizuki appears and offers to go in place of Tomoe. In the end, both go. Mizuki tells Tomoe that he knew why he couldn't go into the water but promised not to tell Nanami. While Nanami and her friends were swimming, Ami suddenly gets pulled into the water and starts to drown. Nanami goes to Tomoe and begs him to help Ami for she could not swim. Tomoe goes into the water and saves Ami. Nanami thanks Tomoe but then a hooded figure appears behind him, rising from the water, thanking him for stepping into the water and enabling him to find Tomoe.