jojifuku
Adults (that is - people outside the intended demographic) wearing nostalgic young children's clothing such as kindergarten uniforms, randoseru, and brands such as Mezzo Piano. Usually considered to be a subcategory of the heisei retro style. Derived from the hashtag "大人なのに女児服着てる" (otonananoni jojifuku ki teru) - "even though I'm an adult, I'm wearing girls' clothes".
This term is sometimes also used to refer to the heisei retro style in general outside of Danbooru, but this tag is for older people wearing children's clothes, and should not be used on pictures of children such as Danbooru post #8895336 - these can be tagged as just heisei retro.