You can upgrade S,B,Y to business and any business to first.
For MAN-MUC there is not many fares published -- just H & B. You need B then.
However for MUC-MAN there is plenty of fares. Q,W,H,B (you need B again) and D,J,C,F

If you are not flying round trip, maybe you can try buying business and upgrade from that

How does F look like on this short flight?