Thank you, Toritoribe - as always.
This one is part of a group of 27 RPPC / real photo post cards which originated in Seattle. A good group with a few shots of Japanese Americans involved in a parade. The man I bought them from purchased the, from an elderly Japanese American lady in Chicago.
In regard to Otani: pretty sure that's a baseball cap he is wearing. Hope to track down the school the ' M ' signifies.