Ore no Musuko ga Hankouki

Rikito Takanashi, a convenience store clerk, loves to have sex with girls, but just as he was enjoying casual sex with several sex friends, his penis suddenly stopped getting erect! Even after that, his situation was so bad that he became unable to ejaculate... One day, he meets Touya Kadokura, a university student, in the park's bathroom. It seems that Touya is an oral pleasurer whose erogenous zone is inside his mouth, and he gets the most pleasure from oral service (=blowjob). When he asks for a try, his son, who was once stubborn, instantly...!! Rikito is happy and tries to enjoy sex with his sex friend, but for some reason, his son's rebellious phase begins again...!

(Source: Gentosha Comics)