Hougetsu Shimamura is a high school student who met Adachi while skipping class on the second floor of the gym in her school when Adachi accidentally walks in on her one day. The two gradually took a liking for each other and began to hang out together all the time. In both manga adaptations, it was Shimamura who walked in on Adachi in the gym when they first met instead of the reverse. Shimamura has waist length, dyed brown hair, which she keeps out of her face with two clips on the right side. Her eyes are also brown. Despite playing basketball in middle school, Shimamura is on the shorter side. She even acknowledges that she is shorter than Adachi. She has a slim figure, but she acknowledges that she isn't really in shape. Several characters, such as Yashiro and Adachi, have touched her 'love handles' much to her dismay. After letting her hair to continue to grow without dying it, her hair eventually changes back from the chestnut color she dyed it back to its natural brown color. Shimamura is a young girl who is a bit on the lazy side as well has a tendency to be an airhead. Adachi often wonders if Shimamura got that trait from her father. Shimamura is conscious of her name being the same of the clothing brand and finds it unpleasant whenever people calls her with her last name. Adachi once said that she had a hard time spelling her name that she would often think of the clothing brand before she could spell her name correctly. During the beginning of the series, Shimamura acknowledges that she has trouble attaching herself to people. Ironically, this is why she originally formed a bond with Adachi since she figured they were similar in this regard. However, her difficulty also had a distinct difference from Adachi. Shimamura finds human relationships as bothersome since she feels that it requires too much effort to maintain such balance. Adachi observes that Shimamura is a 'tolerant' individual but not a warmhearted person. Shimamura often wonders if taking care of her sister is only a duty that was passed onto her as her "big sister" or simply because she loves her. Despite this, Shimamura also understands that there are good things that come from forming relationships. She understands that happiness can be found from having relationships as well. This is what led to her forming a connection with Adachi since she figured they were similar. As the series progresses, Shimamura decides that she doesn't want all her relationships to simply dissolve. While she acknowledges that some of the friendships she has formed will most likely die out over time, she wishes to maintain some connections she formed. While Shimamura isn't sure what to consider her relationship with Adachi at the beginning of the series, she eventually considers it to a relationship that is irreplaceable. After they become a couple, Shimamura initially has some trouble, but she became committed to it. Additionally, she wished for Adachi and herself to become equals in their relationship rather than her needing to depend on Adachi for money among other things. This is evidenced in the timeskip chapters that showcases that she and Adachi maintain a loving relationship well into their early adulthood, and they both were able to afford going on a vacation together. Shimamura seems to have a strong affinity with dogs which began when she was a young girl and met a dog named Gon that was adopted by her grandparents. She looked forward to seeing Gon every time she visited them during the summer and other occasions. Even as he grew to a more advanced age, she still enjoyed spending time with him. She stated that Gon reminds her of Adachi sometimes, and she compares Adachi to a dog repeatedly throughout the series. Similar to her mother, she has an affinity toward teasing others, especially Adachi. However, she is able to restrain herself and show consideration when she knows the people she teases might take her literally. When Adachi asks her what chocolate she likes, Shimamura considered telling her Godiva, but she refrained because she was worried Adachi would actually buy her some and end up spending a significant amount of money. Instead, she simply tells Adachi she likes Milk Chocolate.