On Sunday I followed the Hiyoshi Sanno Festival as it meandered around Matsushima. I found them by following the sound of drums and chanting. Sparrow dancers from Sendai danced energetically while many men in white whirled and lurched a portable shrine around the downtown area.
It is an unusual festival, as it is a Shinto festival to bless and protect the Buddhist Zuiganji Temple, but the lines between religions aren't so hard here in Japan.
The Hiyoshi Sanno Festival takes place each year on the third Sunday of April.
Sendai Motions also has event round-ups but they seem to have gone on break recently: https://www.sendaimotions.com/ A lot of the events listed are annual, though with COVID many have been cancelled.
(I was the former editor for both)