gainax bounce

Know in Japanese as 乳ユラシ ("chichi yurashi", boob shake).

Nowadays it's not at all uncommon for breasts to jiggle in anime. But there was a time when breast motion was the exclusive monopoly of Gainax. The first appearance of the bounce was supposedly in the Daicon IV animation, by Daicon Film, the predecessor of Gainax. It's said that the bounce wasn't in the genga, but was added at the initiative of the douga artist Yoshiyuki Sadamoto. The bounce later appears in Gainax works such as Wings of Honneamise (of which Sadamoto was a sakuga kantoku), Otaku no Video, and Top wo Nerae.

(Source: animesama no shichitenbattou 16 )

According to Japanese Wikipedia Sadamoto became known as Boob Shake Sadamoto.
Updated by grognarg almost 8 years ago