Despite still being in middle school, Shinju is quite tall for her age with a rather mature figure, directly opposing her older sister, who in fact looks much younger than her. Shinju has long, pale pink hair that reaches her shoulders along with light brown eyes. She is usually seen wearing her middle school uniform.
For her cosplay, she dons a black wig resembling Soma's haircut while having her own hair tied back. The shape of her eyes are changed with cosplay tape and she wears extended eyeliner. Her chest is bound back with a B Holder and a sarashi wrap, and she also wears shoulder pads to make her look older and more masculine. She wears Wakana's school uniform, as he points out that its very similar to the one that Soma wears.
Unlike her sister, who is rather blunt and headstrong, Shinju is a timid yet kind-hearted girl. She is shown to get nervous easily, especially when meeting new people, as seen during her first meeting with Gojo and Marin. This aside, Shinju strongly admires and loves her sister, working as her cosplay photographer while also creating an online account to share her sister's work. Shinju likes the Flower Princess Blaze alongside Sajuna and Marin. Her favorite character from the series is the older brother Soma, due to his caring nature, as he reminds Shinju of her sister.
Shinju is aware of her mature figure, particularly her chest, and is shown to get embarrassed about it. She also calls herself "fat" in the Japanese dub of the anime.
Besides her huge "personality" and her shy nature, she is also the photographer of the one and only Sajuna Inui AKA the amazing cosplayer who goes by the name "Juju". Like her friends and "big" sister, she is also interested in trying out cosplay but, contrary to the others, she wishes to cosplay as a boy. Her big chest, however, has proven to be a hurdle in achieving this.
Sajuna Inui: Shinju's older sister (but smaller in build compared to Shinju herself)
- She is the photographer of Sajuna.
- She is also the friend of Marin and Wakana.
- Her name is very similar to Shinji Inui, a character in Initial D.
- "N-nice to meet you... I- I am Shinju Inui!"
- Calendar included in Volume 3 (Blu-ray & DVD)
- Middle school student which are from 12-15 unless she skipped or redid a school year. She is probably closer to a senior than junior middle school student