#now obv we have never got canon ages im not saying this take is objectively correct.

[crowleycorvid]

"The ninja wouldn't be older adults in dragons rising!!" Uh huh. Anyways they're "grown up" teenagers in the Oni trilogy which likely means 18-19, and then were likely in their early 20s in the 11 minute era (bc it happens over ~2 years at least because it was a year between seabound and crystallized). There's then an unknown time period between crystallized and the merge, likely multiple years, because Frohicky heard about the ninja BEFORE the merge as a tadpole. Then there are multiple years between the merge and the ninja reuniting in DR, because sora and arin grew up CONSIDERABLY, as well as Nya. Outright saying the merge was years ago.

I think the youngest the ninja would logically be if we're looking from what vague things we know abt the time between the oni trilogy to now is early 30s, maybe late 20s if you really try to make those year amounts as small as possible