No matter what / whatever happens — an expression emphasizing that something will hold or be done regardless of circumstances.
何があろうと、最後まで諦めない。
No matter what happens, I won't give up until the end.
彼は言った。『何があろうと約束は守る』と。
He said, 'No matter what happens, I will keep my promise.'
何があろうと、まずは安全を確保してください。
Whatever happens, make sure to secure your safety first.