A Kodama (木魅) is a spirit from Japanese folklore, which is believed to live in certain trees. Cutting down a tree which houses a kodama is thought to bring misfortune, and such trees are often marked with shimenawa rope.
"A general name for spirits that inhabit trees. The name is also sometimes used to refer to the trees they live in. The word "kodama" can also mean 'echo' in Japanese, stemming from the belief that mountain echoes are created by these tree spirits. Attempting to cut down a tree inhabited by a kodama is said to bring a curse. "
—Shin Megami Tensei IMAGINE Compendium
Kodama are a regular spawn on Suginami and Nakano fields, including a larger field boss version that appears in multiple locations in Suginami. Early quests and story-line acts regularly feature them. Kodama also appear as one of the two unique bazaar tending demons in Arcadia.