The Focus Gauge is a gameplay element exclusive to Kingdom Hearts Birth by Sleep, Kingdom Hearts Birth by Sleep Final Mix and Kingdom Hearts III. Its shape resembles the Drive Gauge, and is located to the left of the character's portrait on the bottom right corner of the screen. The more focus Terra, Aqua, and Ventus have, the more time they have to lock-on for their Shotlock.
The gauge can be refilled by hitting enemies, much like the Drive Gauge, and by using Ethers. It can also be filled with the Focus Block and Focus Barrier commands, where the gauge is filled on successful blocking of enemy attacks, and the Damage Syphon ability, where the gauge is filled when taking damage from enemy attacks.
In Kingdom Hearts 0.2 Birth by Sleep -A fragmentary passage-, the Focus Gauge is repositioned and redesigned to resemble the D-Link Gauge from the preceding game. The Focus Gauge is filled by collecting Focus Orb prizes dropped by enemies or props, or using Elixirs or Megalixirs. The Focus Gauge is otherwise identical in function to its Birth by Sleep counterpart, depleting at a steady rate when locking onto targets with Prism Rain, and only permanently depleting after Prism Rain is activated.
In Kingdom Hearts III, the Focus gauge retains the exact same functions and position as in 0.2. Rather than equipping individual Shotlocks, each Keyblade has two unique Shotlocks: A standard Shotlock, and one for maximum locks. When the gauge is completely depleted, it enters a "Charge" state. In order to use Shotlocks again, the player must completely refill the gauge while in Charge mode. With the ability "Focus Syphon" equipped, the player can engage in Shotlock mode while Charge mode is active to lock onto enemies and drain Focus orbs to refill the gauge faster.