I did ALL of that stuff. Stayed on the begging screen till it gives the cop warning. Only used the 500 yen coin for the glitch. Found a spreadsheet in the comments listing what food does what transformation. Spent like 15 minutes buying and eating stuff for a specific transformation. STILL didn't get anything to happen. The game has the problem, not me.
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The game is very tedious and specific : If you want to transform. At first just eat any food to survive. however, hoard the food that has the transformation you want, you need A LOT at least by minimum 8 pages of the same food if possible. 10 Plus is better.
Once you're ready, then start to eat and ONLY eat the food that gets you the transformation that you want.