Cut nagaimo into 1cm slices, remove shimeji roots and separate into smaller pieces, and slice green onion diagonally into 1cm pieces.

Slice bacon into 1cm strips.

Heat butter in a pot over medium heat, sauté bacon briefly, then add nagaimo, shimeji, green onion, and seasoning ingredients. Bring to a boil, cover, and simmer on low heat for 3-4 minutes until vegetables are tender.