In the title compound, C(22)H(19)N(5)OS·H(2)O, the naphthalene ring system and the benzene ring [dihedral angle = 85.19 (8)°] make dihedral angles of 87.02 (9) and 14.41 (10)°, respectively, with the pyrazole ring. The mean plane through the 2-methyl-enehydrazinecarbothio-amide group [C-N-N-C(=S)-N; maximum deviation = 0.022 (1) Å] is slightly twisted from the pyrazole ring [dihedral angle = 5.60 (11)°]. In the crystal, mol-ecules are linked by N-H⋯S, N-H⋯O, O-H⋯S, O-H⋯N and C-H⋯S hydrogen bonds into sheets parallel to the ab plane. π-π inter-actions are also observed [centroid-to-centroid distances = 3.7778 (12) and 3.7010 (12) Å].