Do i need to know japanese to play it?
Found a description of the PSP version saying it's a "A Japanese word creation puzzle game" so yeah, I'd guess it's pretty important to know Japanese, inspite of the optimistic last paragraph
QUOTEA Japanese word creation puzzle game where a 100,000 word dictionary keeps track of legal and proper words. Nine game modes are available to keep wordsmiths busy and thinking. In the standard puzzle game mode, a selection of Japanese character on tiles are piled up on the left side of the screen. Select one and place it on an appropriate space on the gameboard to create words and phrases. If your positioning is accepted, the tile is bolted onto the board and a swirl of activity occurs. If your word creation attempt is rejected, an "X" appears along with an unfriendly buzzer. When a puzzle is completed, the boxy golden colored creatures from the game cover bound around in a festival of celebratory madness.Â
 Although Japanese language comprehension skills are recommended in order to fully enjoy Mojipittan, players may also complete the puzzles by trial and error and perhaps even learn a little Japanese along the way.