Kind Heart/guide

School Uniform / Seifuku (せいふく)
Enter the white double doors at the Nexus and you'll arrive at the School. Go to the third floor and enter the leftmost classroom. Go between the desks in front of the entrance and interact with the uniform on one of them.

Smile (えがお)
You must obtain School Uniform before getting this effect.

Enter the white double doors at the Nexus and you'll arrive at the School. Go to the third floor, equip the School Uniform effect and enter the rightmost classroom. (It will not open unless you equip the uniform effect) In that classroom you will see a girl with red twintails standing in front of another girl's desk. The later (who looks like Aitsuki) appears to be crying/hiding her face under her arms/lying on her desk. Interact with her to get the Smile effect.

Snow (ゆき)
Go through the snowy door at the Nexus and you'll enter the Snow World. Interact there with a snowman to get the effect.

Scissors (ハサミ)
Enter the red/dark pink door at the Nexus and you'll arrive at the Bloody Scissors world. Find a pair of tiny blue scissors laying on the ground and interact with them to get this effect.

Panda (バンダ)
Go through the snowy door at the Nexus and you'll enter the Snow World. Find there a small white building that leads to Underwater World, interact with the panda there.

Apple (リンゴ)
Go through the snowy door at the Nexus and you'll enter the Snow World. Interact there with a floating apple and you'll warp to Floating Fruits World. Find there the only lying apple and interact with it.

Doll (にんぎょう)
Enter the red/dark pink door at the Nexus and you'll arrive at the Bloody Scissors world. Interact with a floating heart and you will be warped to the Heartbeat Maze. Interact there with a big red key and you'll warp to a room with stuffed rabbits and a big blonde girl. Interact with her to get the Doll effect.

Wings (はね)
Enter the red/dark pink door at the Nexus and you'll arrive at the Bloody Scissors world. Interact with a floating heart and you will be warped to the Heartbeat Maze. Interact there with a white feather that is blocking your way. It can be a bit tricky to spot it because the floor is also white.