Yosuke and Adachi, for Saki. Oh, the possibilities for clashes. Also Kanji, but that's just because I love Kanji.
Keisuke for Midori, partly because she's already half-expecting, half-dreading him showing up because that means she'll have to, you know, deal with stuff.
Each one of your kids is stuck on a deserted island! Who is the one inmate they'd choose to take with them.