Oh gosh!! Thank you so much!!
I figured out how to get the last two CG's! For the 1st page, bottom row in the center, you have to top Shuu the first time you have sex with him. As for when he adopts a cat, you trigger the event when you spend time with Shuu at the Restaurant on a weekday! After that, spend time with him at the Bookstore on a weekday and you'll get the CG after that! Hope that helps!!!