The Emma flashback is from the final Emma bonding event at the Heimdallr festival as noted. Specifically, it's from the romance path of it, as that scene doesn't happen if you choose the friends option. As for Alisa, yeah, I think she's always the one who appears there. I chose no one in CS3 and she appeared there. There might be added dialogue there if Alisa was picked as Rean's romance there, idk. IIRC for me, Rean thought to himself that Alisa was acting odd but that was about it.
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xp1337: Don't you wish there was a spell-checker that told you when you a word out?