I've been really enjoying this game a lot and I can't wait for the universe to be expanded more, Though for the life of me I could not find Mike or crack the code for the shed. Anyway good game!
Thanks for playing! The code for the shed can be found by counting the flowers in a certain way; it's also a number related to GUMI. Miku is very well hidden, requiring a number of puzzles to be solved. (Hint:, there's a reference to the game Ib involved)