I might not remember it all but
- In the mountain, its located at the bottom left of the rock puzzle
- In the mountain road, its in the shop (you need to push the rocks in order to get there)
- In the village, you have to switch to keiko and fuck the kid that blocks it
- In the outer village, you just push the rock to get it
- In the school, you must switch to keiko to fuck the kid that blocks another mark
- In the train station, you must switch to keiko to fuck the old man till he's fainted
Idk if the outskirts mark exists
Edit: forgot to attach images