This is a rare Japanese B1 Poster (40.6" x 28.7") for American, RKO Pictures adventure film Underwater! (released in Japan as Kaitei no Ogon / 海底の黄).
What makes this poster rare and wonderful is that this poster has original art made just for the Japanese release posters, not on any others.
Contemporary auctioneers and dealers credit comparable early‑1950s Japanese poster art to the illustrator “Miya”(sometimes cataloged as “Miya Uchi / Miyauchi”),

Howard Hughes acquired the rights to the unpublished The Big Rainbow. Partially filmed on location in Mexico and Hawaii, Underwater! was completed in a newly constructed underwater tank in an RKO Radio Pictures soundstage. It was the first RKO film released in Superscope.^[5] The film's budget increased from its initial $300,000 and a large amount of the budget was used on footage cut from the film. Lori Nelson claimed Howard Hughes wanted her for the lead and paid Universal Pictures for her use; however, Jane Russell owed RKO a film. The lead was given to Russell with a part written for Nelson so she could keep her fee.

The film is famous for its 1955 world premiere in Silver Springs, Florida, which was held entirely underwater. Members of the press and invited guests wore aqualungs and bathing suits to view the movie on a submerged screen 20 feet below the surface.