Your overall theme is great! I love learning Japanese and this was a very fun learner. From a gameplay perspective, it was a bit difficult understanding how to put the words together at certain areas. I recommend a popup tutorial visually showing each way the player can use the words to solve a problem. Since this is an educational game, it is more about learning rather than having mindless fun. Art and sound mix well with your theme! I agree with Altabestudio that adding some sprite animations that don't pertain to the problems in the background would help the world feel more alive while learning :)
Viewing post in So to Speak jam comments
Same feedback as before except to also make each word separated so we can drag aka to red instead of dragging the whole entire word "aka shi ngo uda" to red. This feedback is at 49:25 of the VOD https://www.twitch.tv/videos/1821155226