Illustrator Miyama-Zero High School DxD novels made an outburst on Twitter about how the standard of breasts in the industry has increased exaggeratedly over the years. According to Miyama he says:
If you compare the breasts of the girls that appear in some smartphone games with those of the girls in DxD, the latter lose out. Furthermore, the breasts of the DxD protagonists in current cartoons are a little bigger than when I started drawing them, however, even with this increase, they are nothing compared to the extremely huge breasts of girls in new franchises.
Synopsis:
The novel tells the story of an old girls' school that recently became a co-educational school, but it has a secret. Unknown to normal humans, angels and demons are part of the student population. One of these students, Issei Hyoudou, is a very perverted second-year human student who lives a peaceful life. After a normal day of school, Issei is suddenly asked to go out on a date with a girl named Yuuma Amano. After their date, Yuuma takes Issei to a local park and makes him a surprising request. She reveals herself as Raynare, a fallen angel, and mortally pierces Issei with a spear. Suddenly, Rias Gremory, a busty third-year student at Kuoh Academy, appears through a magic circle and revives him.
Additionally, High School DxD became a manga in Dragon Magazine in its September 2008 issue.
Finally, the first volume was released in September of the same year, totaling eighteen volumes in Japan.
Via: Animes In Japan