My mother's remarriage: My mother married my best friend

It's been 10 years since her mother Yu divorced. Finally, Ryota was able to have a new father. For Ryota, who had no happy memories of his father, he was both happy and embarrassing, and there was also the loneliness that his beloved mother might leave. Today is the day I met Yu's new wife for the first time. Ryota was shocked to see the man who came in due to Yu's introduction. The person there was Ryota's best friend since he was a young child. ...And a reality awaited by Ryota's even more unacceptable.