Mizuko (literally: water child) are unborn babies that have died as a result of miscarriage, stillbirth, or abortion.
Mizuko kuyō is a Japanese Buddhistic* memorial rite practiced for the peace of the souls of these babies. The reasons many people in Japan request this rite may include parental grief, desire to comfort
the baby's soul, or fear of retribution from the baby's spirit.
The
mizuko are often represented by small stone statues of Jizo (the guardian of children and travelers), accessorized with various bits of clothing and toys. These commonly include bibs, caps, and pinwheels to keep the souls warm and entertained. Bibs and caps will often be red, perhaps because red looks warm, or perhaps because the Japanese word for red (
aka) is part of the common Japanese word for baby (
akachan).
If you live or travel in Japan, you are sure to have come across these stone statues along the roadside, in both urban and rural areas. They often sit alone under a small roofed shelter at a crossroad, but they can also be in groups of hundreds or thousands, especially in the courtyards of temples that specialize in
Mizuko kuyō rites.
*the reason I call the rite "Buddhistic" rather than "Buddhist," is because there is some question as to its place in historical Buddhism.