We won't loan him out yet, if at all. Wenger always prefers to keep his young players at the club so they gel with other players etc. Also, since he's japanese there wouldn't be much point in loaning him out to another English club, he needs to learn English (if he hasn't already) and gel etc. I expect he'll just play the season in the Reserves and Wenger and Banfield, Brady etc will talk at the end of the season about whether he's ready for first team action, whether that be cup competitions or something else.
I think he's a bit young to be loaned at the moment, and unless he's Wilshere quality he probably won't get first team action for the next couple of seasons as I agree with you; there are so many differences in culture/language which he will need to adapt to, can see him being loaned out in a couple of years times, but it is a little early to say, but that's just my opinion
