User blog comment:B214/High School DxD EX/@comment-3435913-20151107015204

''Zen nodded when he asked it, “Yeah, the number of non-fighter siblings and warriors are balanced. The ones who sent to this era are those who are able to fight and have come of age.”

“The siblings who are sent at this time totaled in ten, which includes me.” Shin continued his brother.''

So Issei doesn't have ten kids, but Twenty. Twenty kids in thirty years time. . . No. Wait-

''. . . The ones who sent to this era are those who are able to fight and have come of age. ''

More than Twenty.

. . . (speechless).