Obscure Internet lore history lesson time.
EccmA is an oldfag 4channer drawfag. He operated under the ethnically-appropriate nickname "chink" from as far as... 2008? Something around that. You can find some of his decades-old art he would post on /i/, /v/, and /tg/ (the familiarity in style and theme is clearly there)
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To assume that he was "underaged" when he briefly made an account and posted here is preposterous. That being said if he claimed so himself, even as an ebing lulz joke typical of a post-ironic 4chan shitposter, mods would've had no choice but to bring down the hammer on his ass.
As for the accusation that his "writing style" implied he's underaged... his English is just shit. Since he's Taiwanese. It's hard to detect sarcasm through text, and doubly so when the text is written by someone with a poor understanding of grammar and stylistics.