Berserk is a negative status caused when a character loses all Sanity Points, causing them to becoming uncontrollable to the player, and perform random actions.
Berserked characters are able to attack allies, and use restorative and boost items and magics on enemies, and can only be cured by the use of SP restoratives; Pure Seeds, leaves, roots and Pure Extract, or by any skill that regains SP - such as Ricardo's Serenata moves.
In addition to the floating icon of a fox-like creature, the background music will also change into the corresponding battle Insanity Track.
Certain characters gain unique moves while berserked, that can't otherwise be seen ingame when under the player's control.
In Shadow Hearts, it is unmentioned, but the only way to unlock Yuri's third-tier fusions' most powerful moves is when he has gone berserk as the fusion monster - whom will instantly use the move the first time they go berserk. The same applies also to Amon and Seraphic Radiance's moves.
In Shadow Hearts: Covenant, in addition to randomly attacking allies or healing enemies, nearly all the characters will perform unique moves, or otherwise bend the normal rules of the gameplay;
- Yuri randomly fuses, using their special skills to attack everyone. He can use these skills even with zero MP.
- Karin skips her turn by falling unconscious.
- Gepetto will play with Cornelia.
- Blanca urinates on someone's leg, dealing single-digit damage.
- Joachim will flex his muscles.
- Lucia is able to use her Tarot Card ability repeatedly.
- Anastasia will search the ground for nearby items, sometimes finding something, other times nothing.
- Kurando will run away, removing him from the battle.
During his brief time as a playable character, berserked Nicolai is able to use Divine Light move - a move normally restricted only when he is playable in the Director's Cut.
In Shadow Hearts: From the New World, similar to Covenant, certain characters will perform unique actions.
- Shania and Johnny randomly fuse, using their special skills to attack everyone. They can use these skills even with zero MP, but will occasionally skip a turn, slumped over.
- Natan will start doing exercise squats.
- Frank spams his Ninja moves, and is able to do so, even with zero MP.
- Hilda's calorie meter fluctuates wildly, changing her form.
- Mao will skips turns by getting drunk, and doing nothing.
- Ricardo will waste time strumming his guitar.