"Backflip and fire a Kamehameha! Use 300 Stamina to fire it even while being damaged! You can also use Ki to fire additional blasts!"
The user charges their into their hand (usually while chanting the familiar KA-ME-HA-ME-HA) then fires an energy wave at the opponent. This technique is often performed when one of the user's arms are lost, thus preventing them from performing the original version. Prior to using the technique, the user does several back-flips to distance themselves from their opponent.
At the end of his Fierce Combination Future Gohan utilized this technique after he lost his arm defending Trunks from the Androids.
"This technique can also be used when taking damage from an opponent. Performs a backflip to avoid attacks. Pressing the button again increases the technique's power."
— Dragon Ball Xenoverse 2 Tutorial description
One-Handed Kamehameha mk. II was first named in Dragon Ball Xenoverse 2 where it appears as one of Future Gohan's Ultimate Skills. It allows the user to use ki to fire an additional blast by imputing the button command a second time.
Though he usually has both arms in most video games, Future Gohan will still use this version of the Kamehameha as part of his one-handed fighting style that is based on his fighting style from the Dragon Ball Z: The History of Trunks special.