Birthday: June 18
Blood type: O

Yui Yuigahama is Hachiman Hikigaya's classmate from Sōbu High School, as well as being the first person helped by the Volunteer Service Club who would later become the third member.

Yui is seen most of the time as a very cheerful, outgoing and friendly girl, in addition to having almost most of the time, a smile which denotes a clear and noticeable joy on her face, whether even when she is sad or upset.

Abilties:
Yui's social skills are excellent, but she is also good, though not particularly outstanding, at academics, intellectuals, and athletics. Other characters always comment on her intelligence and social awareness. She is exceptionally skilled at deducing the mood of others and can make others feel comfortable just by being there. Although some people say that she is dumb, probably due to her naive and somewhat stupid nature, Yui reminds people that she passed high academic standards to get into Sōbu.

She has the ability to sing well and enjoys karaoke. She is a good coordinator and hard worker, able to follow through and give directions when needed (Athletics/Cultural Festivals).

Although she isn't very good at cooking, she tries her best and vows to improve.