After leaving Shin-Ei Animation, he debuted as a screenwriter with Happy Lesson.
Since Happy Lesson, he has been in charge of screenwriting for many series, some of which are Elfen Lied, Your Lie in April, High School DxD, Horimiya, and The Seven Deadly Sins: Revival of The Commandments.
[2] He later worked at Shin-Ei Animation for some time, but later left and became a freelancer.
[1] After going freelance, the first series he was in charge of screenwriting was Happy Lesson.
[2] Since Happy Lesson, Yoshioka has been in charge of screenwriting for many other series.