Kindergartens (Youchi-en, 幼稚園) in Japan usually cater to students around the age of 3-5. Kindergartens may also be located near a elementary school and/or be formally associated with an elementary school.
They are separate from Nursery Schools/Preschools (Hoiku-en, 保育園) which offer more of a child care/day-care service.
Kindergartens do not usually have uniforms, however like elementary school students, they will have a sports cap (normally reversible with two different colours and an elasticated strap for under the chin) and a high visibility yellow hat (that is worn when walking to/from the kindergarten or on school trips).
Some JET's in Oita do teach at Kindergartens, and topics can involve simple English words and phrases including greetings, self introductions, colours, etc.