The system consists of a packed bed of the plant material, which sits above a steam source (boiling water). On the other hand, the HD method involves the complete immersion of plant materials in water, followed by boiling [5], and is widely used at the laboratory scale. Since EO components are volatile and non-polar, the most widely used method for EO analysis is gas chromatography-mass spectrometry (GC-MS), while gas chromatography with flame ionization detection (GC-FID) is used to determine the percentage of EO components [8]. Terpenes, in particular monoter, are the main components in the EOs of conifer families, such as Cupressaceae, the most widely distributed of all gymnosperm families [11; 12]. In view of their odoriferous properties, their lipophilicity, and their broad spectrum of valuable biological properties (e.g., antioxidant properties; inhibitory activity towards acetyl- and butyrylcholinesterase, and \(\alpha\)-amylase and \(\alpha\)-glucosidase; antimicrobial, hepatoprotective, and sedative properties; and skin permeation enhancement) [13], monoter genes find extensive commercial applications especially in the fragrance, flavor, pharmaceutical, and medical fields [14]. Species of the Cupressaceae family, such as _Cryptomeria japonica_ (Thunberg ex [PERSON] f.) D., are among economically important EO producers with interest in various industries and folk medicine [6; 15]. _c. japonica_, an evergreen ornamental tree, is one of the four species belonging to the subfamily Taxodiodeaeae [16]. It is an endemic species of Japan, commonly called Japanese cedar or _sugi_, and is one of the most commercially important plantation trees in Japan and other Asian countries, such as Korea, Taiwan, India, and China, due to its valuable wood characteristics, which include excellent durability for exterior construction, pleasant aroma, insect resistant properties, and a beautiful yellowish-red heartwood color. Moreover, the tree itself is valued in landscaping [17; 18; 19]. Owing to its industrial importance, the chemical composition and biological activities of the extracts and the EOs from different parts of _C. japonica_ as well as the bioactive properties of its isolated components, including flavonoids, terpen, and terpenoids, have been investigated in numerous studies ([1; 20; 21] and the references therein). In particular, there have been several reports over the last eight decades [22] on the bioactivity and chemical composition of the EOs from _C. japonica_ leaves, since they are usually discarded by the wood industry. The leaf EO of this plant from various countries has demonstrated a broad range of bioactivities, including analgesic [23], antibacterial [24; 25; 26; 27], antifungal [20; 26; 27], antiinflammatory [25], antimelanogenesis [28], antioxidant [15], antitussive [29], antiulcer [30], anxiolytic [23], cancer chemopre [31], neuropharmacological [32], whitening [15], antitermite [33], insecticidal [34], mosquito larvicidal [35; 36; 37], mosquito repellent [38], and silverfish repellent [34] properties. Therefore, the interest in leaf EO from _C. japonica_ as an eco-resource of valuable bioactive components is rapidly increasing. Concerning the leaf EO composition of this plant from various countries, great differences not only in the identity of the EO components but also in their percentage were found in several studies ([1; 17] and the references therein), as expected. For the extraction of EO from _C. japonica_ leaves, the majority of the referenced studies have utilized the standard HD method. Moreover, few studies [33] have reported the effects of different distillation methods on the properties of _C. japonica_ leaf EO (e.g., color, odor, yield, chemical composition, and bioactivity). In Azores Archipelago (Portugal), located in the northern Mid-Atlantic Ridge and composed of nine volcanic islands, _C. japonica_, known in Portugal as \"criptomeria\", was introduced from Japan in the mid-19 th century and was extensively cultivated for economic uses. Moreover, _C.