Umi Adachi

In the story, she is the third girl to become friends with Akane and is Akane's first female friend. She has black hair tied in a single braid at the back of her head (in the sixth grade, she often wears two braids). She wears glasses and is 140 cm tall as of the first term of sixth grade. She mostly dresses in subdued outfits, pairing cardigans with pants, and except for special occasions like taking commemorative photo stickers, she does not wear skirts. She lives in a single-family home near Daichi's house with her parents, and her father is a school biology teacher.

She has a gentle yet strong sense of justice and mature thoughts. Daichi describes her calm and gentle demeanor as "soft glasses." She likes creatures, especially snakes and lizards, and dashes towards rare creatures. She has a crush on Daichi, and it was through consulting Akane about this that they became friends, thereafter calling each other "Akane-chan" and "Umi-chan." Thus, Akane also knows about Umi's feelings for Daichi. Umi's parents seem to have known about her feelings for Daichi for a while. Unfortunately, as of now, the laid-back Daichi has not noticed Umi's feelings. In the sixth grade, the appearance of the beautiful and mature Aina, who gets along well with Daichi, makes Umi jealous and cautious, but after clearing up the misunderstanding, Umi and Aina seem to get along well, bonding over discussions about love. Umi, with her strong sense of justice, is displeased with the bullying towards Akane but due to her gentle nature, she couldn't strongly protest against Kotarō's badmouthing of Akane or express more than mild dissatisfaction with Sumire's behavior. When Taiyō called Akane "Grim Reaper," Umi was initially upset, but after seeing Akane's reaction, she realized Akane's feelings for Taiyō and has since shown no displeasure. After learning about Akane's feelings, she internally reacts like Yukiko and supports the relationship between Akane and Taiyō.