Why, yes, Mirai is an alien.

[sennetari]

"You know, I've often wondered why you don't seem to know basic things the rest of us are familiar with. I want to say it's because you are from another country, but you don't look like a foreigner enough for that to be a reason."

Mirai leaned back in his chair, looking uncomfortable. "I'm sure I don't understand what you mean, Teppei-san."

Teppei sighed. "Guess not. Come here for a moment, will you?" He walked back to his workstation, while Mirai awkwardly follow.

"Here." Teppei typed in "ja.wikipedia.org" on his laptop computer. "Search on this site if you are stumped on anything. And you better not be using your memory display, but a regular computer while doing so."

"Why not?"

"The signals sent from a memory display can be traced back to its user. Now, I think only the captain and those higher can check the activities on your memory display, but you never know. Better be safe than sorry."

It was Mirai's turn to sigh. "I still don't understand your need for secrecy, Teppei-san. You don't trust our teammates that much?"

Teppei stared at Mirai. "It is not my need for secrecy, it is yours!" He took Mirai's hand. "I'm telling you all this for your own good, Mirai-kun. The others are still oblivious, but even they might catch on if you ask too many questions."

"Catch on?"

"That you come from another country, of course."

(Yup, I was going to use this snippet for a fic, but change my mind.)