This article is from the Final-Fantasy and other Square Soft Games FAQ, by email@example.com (Nick Zitzmann) with numerous contributions by others.
You can reset the game at any time by pressing & holding L1, L2, R1, R2,
Select, and Start at the same time.
6.6.3 -Final Fantasy VII: All 7 Fever
Should a character's current HP reach 7777, they will experience a
phenomenon called "All 7 Fever".
While a character has All 7 Fever, their attack will always connect for
7777 points of damage. However, once the battle is over, the player with
All 7 Fever will have 1 HP remaining.