Eri is deeply terrified of Kai. Similar to how he treats his members, Kai only values Eri because of her use, this being her Quirk that aids Kai in creating a world with no Quirks. Due to his own Quirk, Overhaul, Kai did not hesitate to endanger Eri's life, as he could simply fix her if he acts soon enough. In addition to using Eri as a lab rat, Kai mentally abused her by telling her that her existence only causes problems for everyone around her. As a result of this, Eri developed a habit of bearing the abuse from Kai's research efforts, believing there was nothing else for her. She consequently lost her ability to smile After her rescue from the Shie Hassaikai, Eri still wasn't able to smile. The memories of Kai's torture leave her doubtful and afraid in her new life. However, with the care of the U.A. staff and students, she is able to smile and become happy at the U.A. School Festival showing she is recovering from Kai's past influences.
