The main character "Nick" is able to transform into "Captain Rainbow" a tokusatsu-styled superhero wielding a yo-yo, with a wish to restore his lost popularity. To restore his popularity, Nick ventures to Minmin Island; an island where wishes are said to come true, he'll meet a vast array of past minor Nintendo characters with their own dreams and wishes on his journey. The game features a stylized cartoon look similar to Skip's other games.
Right, that makes perfect sense to us... Perhaps Captain Rainbow can only really be appreciated in its native Japan, which is why there has been very little info regarding a Western release at present, perhaps expect a rename before it does so.
Either way (we're liberal like that) the game will be released in Japan on Aug 28th.