The attack works by concentrating all the energy in his cells into one punch. Thus, Ryohei keeps his right fist in perfect condition for times of great need.
During Ryohei's training in the Varia Arc, Colonnello shot him with a spiritually condensed Bullet that risked death. By surviving, Ryohei's potential was unlocked, enabling him to unleash his Maximum Cannon.
While fighting in the Sun Ring Battle, Ryohei was also able to use Maximum Cannon to fire the salt crystals from his sweat in order to break the lights that blinded him. At only 90% power the blow wasn't strong enough to beat Lussuria, but once Kyoko Sasagawa arrived, his cell transfer rate went up to 100%. He was then able to destroy Lussuria's Metal Knee.
Once Ryohei acquired his Vongola Box Weapon in the future, Maximum Cannon also produces Sun Flames to attack the enemy, striking those at a distance in a similar way to the punches of the First Generation Sun Guardian.