Kan Lahan is a character from Apothecary Diaries. He is a clever civil official, a numbers genius, and Maomao’s biological cousin who's also her adoptive brother. He is known for managing imperial finances, loving money, and viewing the world through calculations. He is part of an eccentric family (The La Clan) known for extreme intellectual talents and unique personalities. He views the world through a numerical lens, analyzing situations, assets, and people based on data, calculations, and strategic value. He is exceptionally cheap, loves money, and constantly looks for financial leverage, sometimes trying to exploit others or situations for personal and clan profit. True to the eccentric bloodline and quirks of the La Clan, he behaves in odd, unsettling ways—such as proposing odd logical experiments or boundary-pushing ideas. Unlike his eccentric adoptive father Lakan, Lahan handles social situations well and prefers pulling strings quietly behind the scenes to avoid getting his hands dirty. He maintains an easygoing and reasonable demeanor/approachable facade, masking a sharp, opportunistic intellect used to investigate corruption and manage state finances. Kan Lahan works as a civil official and accountant in the Outer Court of the Imperial Palace despite being only nineteen. Kan Lahan is a slender young man of average height with a highly intelligent, studious look. He is typically seen wearing the standard robes of a mid-ranking civil official, which reflect his formal role in the imperial court. He wears spectacles, which is a rare and distinct trait in his society. He has sharp, calm features with a generally polite but calculating expression. His dark hair is neatly tied up or styled under his official headwear. He wears a yuanlingshan (or yuanlingpao), a traditional round-collared robe commonly issued to civil officials. The fabric is a deep, dark blue. Underneath his primary official robe, a clean white inner collar (zhongyi) peeks through at the neck. He sports a traditional official's hat known as a futou, which features stiffened wing-like extensions sticking out from the back. He wears dark, high-top court official boots, historically referred to as zao. He is rarely seen without his abacus, which he carries with him everywhere to tally up numbers, finances, and calculations.

Kan Lakan is a brilliant, eccentric military strategist and Grand Commandant in the Imperial Palace. He serves as the Grand Commandant, holding one of the highest military positions in the nation. He is the head of the influential La Clan. He is an unmatched player of strategy games like shogi and Go, and he has a rare talent for finding capable people. He suffers from prosopagnosia, meaning he cannot recognize ordinary human faces. He overcomes his condition by picturing people as shogi pieces based on their roles, a method taught by his uncle. He wears a decorative monocle over narrow eyes. He has narrow, sharp eyes that often look calculating or squinted. He has long, dark hair tied back in a traditional topknot or ponytail. He keeps a small, well-trimmed goatee and thin mustache. He wears high-ranking military robes, often featuring intricate patterns, long sleeves, and a heavy official hat. He appears as a man in his late 30s to early 40s.