User blog comment:B214/High School DxD EX/@comment-16281343-20150724130341

Apparently, Issei and Rias's son appears in EX1.

His name is イクス (Ikusu). イッセー (Issei) + サーゼクス(Saazekusu)

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I have yet to secure myself a raw of EX1. What I have right now is just an image of the very first page with most of it covered up.

Sadly, only 9 lines are complete and the 10th is halved.

Anyway, the first four lines are one of the quotes in EX that goes "This story is top secret and only a few dignitaries know about it. (...) This information should never get out of this table (...) but it's true that this information is useful"

The next available lines are in Azazel's POV. According to him, he was consulted by Rias because there are suspicious things going around her territory and they're sure that it is not a Stray Devil.

The next sentence mentions the words "Khaos Brigade" and "Sacred Gears".

That's all I have about EX1 ... for know.