Some Russian consonants (ш, ж, ч, щ, ц) do not form hard/soft pairs.
If a noun has one of such consonants before the final ‘ь’ (i. e. it ends in -шь, -жь, -чь, or -щь), then it definitely is feminine.
That's because of a (strange) spelling rule. According to it the letter ‘ь’ must be placed after these consonants (except ц) only if the noun is feminine (this ‘ь’ doesn't affect the pronunciation).
For example:
мышь — feminine (pronounced [mɨʂ])
шиш — masculine (pronounced [ʂɨʂ])
ложь — feminine (pronounced [ɫoʂ])
нож — masculine (pronounced [noʂ])
печь — feminine (pronounced [pʲeʨ])
меч — masculine (pronounced [mʲeʨ])
вещь — feminine (pronounced [vʲeɕː])
клещ — masculine (pronounced [klʲeɕː])