Aria finally realizes her own feelings while attending the sports day, where she is filled with confusion and excitement.
Meanwhile, Masachika prepares for the birthday party he had promised, but since he is not used to choosing gifts, he has a very hard time.
Masachika, who was teased by Yuki and pushed around, decides to tell his partner something important on the day of the birthday party.

"happy birthday.
“I sincerely thank you for meeting me.”

【I am the one who should be thankful.】

Arya and Masachika give each other blessings and gratitude for the miracle of meeting each other.
However, an ominous shadow approaches the two people who were smoothly developing their bond.
The hidden dangers in everyday life begin to stir… …?!

A youth romantic comedy with a hugely popular Russian high school girl!! A heart-pounding birthday party episode!!