Very vintage, small sized child's indigo cotton hanten - sometimes called a happi coat. No telling how old it is.
A horizontal brick-like pattern on the lower back and red stripes across the shoulders. The kanji says yutakagumi on the back and toyosakarikai on the front. Yutaka means to prosper and gumi (or kumi) means group.
Small size. Wearable but great for display. Very collectible.
Indigo was often used to dye these festive jackets. See video below on indigo dyeing in Japan.