Kohaku, a male Shiba Inu Jewelpet, features cream-yellow fur, white paws, a tail stripe, and light brown markings on his inner ears and above his eyes. His jewel eyes combine orange and brown amber, and he wears a red bandanna fastened by an orange flower-shaped amber accessory.

In "Jewelpet", Kohaku partners with Aojiso of the Phantom Herb Thieves. Initially imprisoned in Jewel Charm form, Rinko and Ruby awaken him to break Aojiso’s curse. During "Jewelpet Twinkle☆", he apprentices under the Fountain Dragon and mentors the human Leon, instilling teamwork values that secure Kohaku his final Jewel Stone.

His allegiance changes in "Jewelpet Kira☆Deco!" when he joins the antagonistic Decoranain as one of the Shitennou (Four Heavenly Kings). He employs deceptive charm to provoke conflicts, exemplified in episode 44. Exposure to Kaiser’s corruption in episode 48 reverts Kohaku and ally Tour into Jewel Charms, removing them from the series.

For "Jewelpet Happiness", Kohaku emulates human Kousuke’s demeanor to court a love interest—later revealed as the long-haired male Apel—forming a Magic Gem partnership with Kousuke. In "Lady Jewelpet", Luea selects him for the Petite Ladies’ dog-walking challenge due to his aristocratic aura, pairing him with human Lillian.

Personality-wise, Kohaku exhibits energetic ambition, though anime depictions accentuate his clumsiness and sensitivity. He supports allies and occasionally suffixes sentences with "shiba", nodding to his breed. His magic centers on leadership enhancement and economic fortune, varying by series: luck-based in "Jewelpet", group guidance in "Twinkle☆", and wealth attraction in supplementary materials. Early anime appearances recurrently highlight his sneezing susceptibility.