I'm very good at scientific terms, particularly the ones that are derived from Latin. My pronunciation isn't always perfect. If we were going to talk about something I don't know about, then, maybe... [ Dazai thinks for a minute. He's familiar with a lot of jargon that most people might not know in multiple languages, but, you know how it is when you're raised as a weird sort of genius game theory child soldier. ]

... I'm very bad at casual small talk and slang. [ Dazai considers this, and then, with his best attempt at casual American interactions: ]

I'm Dazai Osamu, it's ... cool ... to meet you? [ Please, he speaks like he's from the 1800s even in Japanese half the time. ] ... radical ... ?

[ Despite the fact that his vocabulary is lacking -- the English itself is great. It's possible that his alternate self just also speaks like a Victorian gentleman. ]