Yamashiro Haruna♀

Haruna is the younger of the Yamashiro sisters, and is introduced to the player as a girl whose self-imposed duty is to keep Yuuichi in check. She is a student at Chihara University (the same university attended by AneImo2's Kirishima Mizuki) and occupies the rest of her time with her part-time job as a waitress.

Unlike her older sister, Haruna is more level-headed when it comes to dealing with Yuuichi. She has spent so much time around our protagonist that she has mastered the ability to read him. She's especially critical of Yuuichi's tendency to look at the women in his life with slightly ecchi eyes, and often calls him out on it as soon as she notices it. She also criticizes the protagonist due to his severe indecisiveness, especially when it comes to his relationship with Wakaba.

Despite the strong and aggressive front she puts on around the protagonist, Haruna has a softer side that is very much in love with Yuuichi, but knows her attraction to him is unnatural due to them being siblings.

[From Moroboshi Yuumei's review]