Isodendrion hosakae is a branched shrub, reaching heights of 3–8 decimeters, with pilose (hairs antrorse) branches and leafy up to approximately 20 cm below the apex. The leaves are simple and alternate, with narrowly elliptic blades to lanceolate, measuring 3–7 cm in length and 0.6–2 cm in width, featuring an acute to slightly acuminate apex and an attenuate base. These coriaceous leaves have crenulate–serrulate margins with whitish ciliate edges and are conspicuously reticulate-veined; the veins on the upper surface are slightly impressed, while those on the lower surface are somewhat raised and sparsely appressed pilose, particularly along the veins. The petioles, 0.3–1.2 cm long, are appressed whitish pilose (hairs antrorse), and the stipules are slightly asymmetrical and ovate, measuring 2.5–4mm in length. It produces solitary, fragrant, bisexual (perfect) flowers axillary on short pedicels, with the calyx made up of 5 lanceolate sepals, 4.5–6 mm long, becoming membranous toward the whitish ciliate margins. The corolla comprises 5 greenish-yellow petals, varying lengths among the upper, lateral, and lower petals. It has 5 subequal stamens with filaments approximately 1.3 mm long and anthers about 1.2–1.3 mm long. The ovary is superior, 3-carpellate, 1-celled, with parietal placentation, anatropous ovules, a single filiform, sigmoid style, and an enlarged and excavated apex. The fruits are green, tinged, dull red ellipsoid capsules, 12–16 mm long, 3-valved, and tipped with a persistent style. Seeds are olive with a dark spot near the middle, obovoid, 3 – 4 mm long, and approximately 2 mm in diameter, containing fleshy, oily endosperm. It thrives in dry shrubland dominated by Dodonaea, Sophora, Wikstroemia, and Santalum between 900–1030 meters.