Take a look at Sendai Shirayuri Gakuen, though, I don't think this is a dumping ground for diplomats' children. Everything seems to be aimed towards Japanese students, and they do have programs other than an English program. And their English-language site is severely truncated, you'd think that if they were actively courting the foreigner market as their primary market, they wouldn't do
that.
And, I was wrong about them not having any boarding, I think... Google Translate isn't perfect, though, but this is from the admissions FAQ for the junior high school:
What are dormitory and interview?
This is the time of the dormitory interview, but it is in the order of entrance exam interview → → dormitory interview. I will give you the day time. The guidelines for applicants, there are items in the dormitory qualification. Because I judge in the form along the dormitory qualification, the decision of whether life in the dormitory, please face the interview Omotte consciousness to the communal life, to protect the rule, that master of its own.
And, this, from their English-language page on their high school... (I know, Lilly couldn't have gone THERE, due to being at Yamaku, but...)
The mission of Sendai Shirayuri Gakuen is to nurture pupils to live honourably before God. Through the promotion of humanity, moral values, and global awareness, pupils are guided toward looking beyond their own needs and fostering the spirit and capacity to help others.
For some reason, that reminds me of Lilly, she takes that to 11. (Or full retard, as the case may be.)
Edit: And, if they were in Natori or Iwanuma as I think... then Sendai Shirayuri Gakuen is on the wrong end of Sendai, unless they used the dorms ANYWAY, which I'm pretty sure they didn't. Damnit.