first one: sick shuu - keep visiting him at his house, at some point the scene will happen;
2nd: beach trip CG;
last one: fan meeting
and the shiba's dog costume: dog appears in one of the classes (it'll triggers a CG too), after the dog shows up, the love hotel bear will make you an offer, go to the love hotel at night and the bear will offer you a dog costume (cost: 20k); for the scene to happen, you have to top shiba at least once, after buying the costume, at some point the scene will happen (it took a while to appear for me, so don't worry);