Rerolling:

Before starting the game you'll be prompted with a ToC pop up followed by the asset download options:
- Left button for full download / Middle button for minimumum (200MB~)
- If you're rerolling using the file deletion method then its better to choose the full download option first as it'll reduce the time spent on loading / downloading screens in subsequent rerolls.
- If you're rerolling by deleting app data then just stick with the minimum download.

File Deletion Method (Skips the initial download):
- Navigate to data/data/com.square_enix.android_googleplay.TojinomikoTomoshibi
- Delete both the "Shared Preferences" folder and the data00 file in the "files" folder, not the folder itself.

Finishing the tutorial gives you a free gatcha roll for a 3* or 4* character
Claiming the rewards from your present box should give enough gems for a 10 roll

Reroll Tierlists:
https://gamewith.jp/tojinomiko/article/show/95661
http://xn--l8j5d9a2a.com/tojitomo-risemara

Gatcha Rates:
The pool is split between Main and Support cards
4* 3% / 6%
3* 12% / 18%
2* 25% / 36%