Longtime best friend of Ayumu Shiiba up until the day of the test results.
Before the start of the manga, Yuko Shinozuka became best friends with Ayumu Shiiba and they were inseperable. However, as Ayumu studied, poor Yuko was unable to deal with her studies because she didn't have any backup notes and the situation became her downfall later. Her true self came out and hurtfully called the relationship off with Ayumu, which started Ayumu's emotional issues.
Yuko's first appeared in the first volume of the "Life" manga, which was created by Keiko Suenobu. She was featured as an antagonist for a short time.