She is an energetic tomboy who likes to tease Seishuu, but her actions are more like bullying. She is also rather blunt when she speaks and just tells what's on her mind. Despite this she can be rather caring as shown in episode 6 where she was worried that when Kanzaki Kosuke who beat Seishuu in a calligraphy contest and took first prize came to visit, she tried to avoid the topic of his name so he wouldn't reveal his identity and cause Seishuu to relive his depression from losing and commit suicide (although as it turned out Seishuu knew from the beginning who he was but was less bothered with him than expected).
Miwa has gained some of Seishuu's mannerisms, as she was depressed like he was at being second place at calligraphy while Tamako earned first.
She previously used Seishuu's house, as a base together with Tamako and Naru. She and Tamako welcomed themselves into Seishuu's house and started looking for the things they used to have in there. She argued with him at first about how the house was their base at first, but warmed up to him soon afterwards. Most of the time, she invites herself in his house usually with Tamako and Naru.
Her best friend. They are very close and go to the same school together, possibly in the same class too. Miwa seems to be un-aware of Tama's fujoshi side, but knows that she wants to make manga.
Miwa is pretty fond of "Sensei" just like the others, and she does care for him. She doesn't want him to leave the island, as shown in episode 8 when Tama brought up that subject, she quickly changed it to something else.
Hiroshi and Miwa have a pretty close bond. Miwa calls him "Hiro-nii".
Miwa influences Naru a lot, teaching her weird things that she shouldn't know. They are similar on terms that they're both very out-going and cheerful.
- She has five copies of Seishuu's house keys, one is with her, one with Tamako, one with Hiroshi, a spare one and one which she'd lost in the mountains. Although, in episode 9, Seishuu finds the one she'd lost.
- She's the one who teaches Naru weird stuff (usually things which she shouldn't know).