Nakizumo at first, second, and possibly third glance looks like some kind of baby psychological torture but the ritual is actually for the babies' health and wellbeing. Nakizumo is sumo wrestlers trying to get babies to cry. The first baby to cry wins.
The gyoji (referee) will goad the babies on by saying "nake! nake!" which means cry. The wrestlers will gently rock the babies and grimace at them. If that doesn't work then the judges come into the ring with devil masks to scare the little ones into crying. All of this seems like some bizarre baby torture but in old days when infant mortality was high a crying baby was seen as a healthy baby.
Nakizumo goes back some 400 years and parents still bring their babies to have them scared for good luck and long life.
Sensoji Temple in Asakusa, Tokyo
Competing babies get a blessing first
You look ridiculous
I'm gonna punch you, old man!