Re Rive (輪廻夢)/guide

Light (光)
Enter the light blue archway. Go north-east and walk between the two pillars pictured to the right. Go right to a crossroads. Take the north path. Interact with the ball of light.

School Uniform (校服)
Enter the open cream door. Go right to the next hallway. After that, right and down (don't enter any doors). Follow the hallway down and left until you reach a row of spikes. Enter the door beside said spikes. Interact with the uniform.

Parasite Rabbit (寄生兔)
Interact with the slanted pink door. Go south-west and enter the frog head. Interact with the stuffed rabbit.