It came as a bit of a surprise to see Mizuho make a guest appearance as a scientist interested in robots in ToHeart – Remember my Memories. I never played much of the ToHeart game, so I wonder if this reference to Shizuku is just in the anime.
The picture in the middle of Feel looks like Kanako, so it seems like Mizuho built a maid robot that looks like her friend. I never played Shizuku, but the fate of Kanako appears to be rather grim…
Edit: SickC noted that the Himeyuri twins, Sango and Ruri, from ToHeart2 also make an appearance so I added that picture. Himeyuri vs. Kurusugawa… hmm…