Bleach: The Strongest Kenpachi Starting from Signing In

Ru Yueming travels to the world of Death God and unlocks the sign-in system.
I thought that by signing in every day, I could become stronger, and soon I would become the Captain-Commander, serve in the Zero Division, punch Yhwach, kick the Soul King, and marry Unohana...
However, the system's art style was not quite what he had expected.
[Check-in complete! Receive Yamamoto Shigekuni's secret-recipe roasted sweet potato!]
[Check-in complete. Obtain exclusive affix: King of Basic Attacks, effect...]
[Check-in complete, received Retsu Unohana's...]
Ru Yueming's eyes suddenly lit up; it didn't seem like a bad idea after all!