This paper is the fourth part of taxonomic notes of Japanese Cryptinae (Hymenoptera, Ichneumonidae). In this study, 11 genera of tribe Aptesini Smith & Shenefelt, 1955 and six genera of tribe Cryptini Kirby, 1837 are studied. Plectocryptus Thomson, 1873 is new to Japan. The following 32 new species and one new subspecies are described: Aconias fujiei sp. nov.; Ac. longisetosus sp. nov.; Aptesis albicoxalis sp. nov.; Ap. ezoensis sp. nov.; Ap. jinbensis sp. nov.; Ap. minor sp. nov.; Ap. yamauchii sp. nov.; Cubocephalus asiaticus sp. nov.; C. confusus sp. nov.; C. nanus sp. nov.; C. sapporensis sp. nov.; C. uryuensis sp. nov.; Giraudia kurenai sp. nov.; Gi. nana sp. nov.; Javra albotrochantellata sp. nov.; J. gigantea sp. nov.; J. japonica sp. nov.; J. minamiashigarensis sp. nov.; J. minuta sp. nov.; J. tenuis sp. nov.; Megaplectes bicornis sp. nov.; Meg. konishii sp. nov.; Parmortha albitarsale sp. nov.; Pa. gigantea sp. nov.; Pa. nigra sp. nov.; Plectocryptus japonicus sp. nov.; Pleolophus obtusus sp. nov.; Schenkia alpina sp. nov.; S. japonica sp. nov.; S. minuta sp. nov.; S. uryuensis sp. nov.; Goryphus albofasciatus erabu subsp. nov.; Listrognathus (Listrognathus) octoguttatus sp. nov. The following three species and one subspecies are newly recorded from Japan: Ap. flagitator (Rossi, 1794); Ap. melana Li & Sheng, 2013; Idiolispa analis analis (Gravenhorst, 1807); L. (L.) yunnanensis He & Chen, 1996. The following three new synonyms are proposed: Ac. tarsatus (Bridgman, 1881) = Plec. albitarsis Uchida, 1936 Syn. nov.; Parmortha maruyamensis (Uchida, 1930) = Cratocryptus microstriatellus Uchida, 1952 Syn. nov.; Nippocryptus alutaceus (Tschek, 1871) = Caenocryptus canaliculatus Momoi, 1968 Syn. nov. Furthermore, the generic position of Aptesis opaca (Cushman, 1937) changed to Oresbius Marshall, 1867 (comb. nov.) and a new replaced name, O. cushmani nom. nov. is proposed. Some redescriptions, new distribution records, and keys to species in 10 genera are also provided.