Isana and Takamina already met each other since they were a child (Isana: 4 years old and Takamina: 3 years old). However Isana having an amnesia after that so he forgot about Takamina. They met again when Isana's step-
parents and Takamina's step-parents were going to creating a korean idol project, SHU Projex. Takamina met Isana again and calling he Joohyun (Isana's korean name) for the first time when Isana still doesn't remember her. Then, after knowing Takamina's name Isana got his memories again and starts calling her
as Sunny (Takamina's korean name) and always calling her like that. After Isana leave 48 Dormitory and transferred to SHU Dormitory sometimes he comes ONLY to see Takamina when every students don't in the dormitory and Takamina always showing her tsundere personality.