Komasan is a komainu, closely resembling a shiba inu with long, blue fiery eyebrows that look similar to hitodama flames. Throughout his body and head, he has ivory-colored fur with a light blue stomach, tail, and inner ears. His eyes are a lime-green color and he has red swirls on his cheeks and hips. Komasan's eyebrow flames are actual fires, but can rarely cause burns.
He carries a green furoshiki (a cloth that can be wrapped, which is used for storing and carrying items) with a white spiral patterns wrapped around his shoulders. He uses it to carry various objects, in the event of finding a new place to live or for travelling to other places. In later appearances, he wears a green sling pouch which was given by Komajiro in the anime series, where he uses it to carry extra items inside of it. This detail is somewhat retained in his human disguise.
When Komasan puts a leaf on top of his head, he can transform into a human for his disguise. His human appearance is of a male teenager with black hair, eyes with black pupils with a facial appearance resembling the original form of the Yo-kai, while he wears a beige blazer with a shirt, necklace and dark-brown pants. He sometimes uses it in the anime series, most notably in the Komasan In Love segments, even though in Kaptain Komasan, he is seen in his original form to the viewer.
Komasan is a shy, yet curious Yo-kai that likes discovering new things. He was once a guardian at a shrine for centuries until it was demolished, leaving him to wander into the city and get used to modern life. In the video games, he's depicted as initially timid and cowardly, a point that earns him the mockery of Springdale's guardian Kyubi.
He is portrayed as a country bumpkin and usually speaks with a stereotypical country dialect; this manifests as a Southern accent, where he tends to add slang to his sentences. In the Japanese version, he talks in a Nagano dialect while he adds -zura suffix to his sentences. When excited, frightened, or surprised, he usually exclaims "Oh my swirls!" (Japanese: もんげー！,Monge~!), though on several exceptions he says other stuff in English version.
He is also friendly and peaceful, and usually tends to care about his friends. Despite that, listening to long monologues usually causes a distraction for him. Komasan usually does not resort to violence in the middle of a conflict, even if he gets angry which is a rare occurrence for him. Though Komasan is smart when learning about new skills, he also tends to make odd decisions which usually results in a better option for him.
Despite rarely using his powers in most depictions, Komasan can control fire to a degree and summon hitodama flames to set fire on his opponents.
In the manga and anime series, he rarely uses fists for fighting when in the middle of a conflict and tends to call others for help. Occasionally, Komasan uses weapons like a bazooka which are usually provided by his friends but he isn't good at handling weaponry.
In the anime, he has had a large number of segments, starting with Komasan In the City where he tries his best to learn as much about the city as he can to present himself as a good role model to his younger brother, Komajiro. He pretends to be very knowledgeable about city life. However, Komajiro has a high capacity to adapt to the city and soon becomes a DJ at a nightclub. By the end of this mini-series, he'd accepted his general preference for the country, and retained Komajiro's admiration by saving him from getting beat up. They ultimately decided to remain in the city, taking up residence at a small riverside house.
"Komasan" is the "koma" half of komainu followed by the -san honorific.
Komasan is based on a komainu, a guardian statue halfway between lion and dog. Originating from Chinese guardian lions, they guard the entrance or inner building of Shintoist shrines. They usually come in male-female pairs, placed at each side of the entrance. Because of Buddhist influences, the right one's mouth is always open while the left one's closed, pronouncing "a" and "um", the first and last letter of the Sanskrit alphabet: together they form the sacred syllable Aum. Incidentally, these letters are the original names of Komasan and Komajiro's Alpha and Omega skills.
While Komasan is based primarily on a komainu, his leaf transformation and love of food are traits often attributed to tanukis.
Komasan's initial design during creation was "a friend like Jibanyan" taking notes from the latter's design except by giving a features of a dog, and eventually making the head into a bean-shape, which would depict his personality.
There's alternate artwork of Komasan, which depicts him with a thumb which he is never seen with in the games or anime.
In episodes of the Yo-kai Watch anime before EP029, he and Komajiro had a slightly different-looking appearance compared to newer episodes, closely resembling his artwork from the game with thinner arms and legs and a less rounder head shape.
In EP058, Komajiro says that he and Komasan are over 300 years old.
He was voiced by Melissa Hutchison in the first two seasons of the English-dubbed anime, and in the video games.
In the Portuguese dub, Komasan speaks with a Porto accent. As Porto is one of the most urbanized Portuguese districts, this contradicts his personality of a country bumpkin.
Komasan and Komajiro are the only mascot Yo-kai to have a completely different name in the Korean localization.