1. But, like and, is a common transitional word and often begins sentences. When it is used in the middle of a sentence as a coordinating conjunction like and or so, it is not followed by a comma unless the comma is one of a pair setting off a parenthetical expression: His political affiliations make no difference, but his lack of ethics does. The cast is nearly complete, but, our efforts notwithstanding, we lack a star. See also and, so¹.
2, 10. When but is understood as a conjunction and the pronoun following it is understood as the subject of an incompletely expressed clause, the pronoun is in the subjective case: Everyone lost faith in the plan but she ( did not lose faith ). In virtually identical contexts, when but is understood as a preposition, the pronoun following it is in the objective case: Everyone lost faith but her. The prepositional use is more common. However, when prepositional but and its following pronoun occur near the beginning of a sentence, the subjective case often appears: Everyone but she lost faith in the plan. See also doubt, than.

Did you mean butsu?