In psychology, it is important to understand the mechanism behind human behavior.

This rare stone is something I found in the mountains.

This rock contains pyroxene.

I plan to go home this summer.

I plan to return to my hometown for the first time in a long time this summer.

A strange voice was heard from his room.

He was reading a book while smoking a kiseru.

He didn't buy a ticket in order to cheat on his train fare.

He was deep in thought with a pipe in his mouth.

He cheated on his train fare by 'smoking a pipe'.