Meme Oshino is a middle-aged nomadic specialist in supernatural phenomena, known as oddities. He operates as a neutral mediator who restores balance between humans and aberrations rather than exterminating them. His appearance features a lanky physique, short spiky blond hair often in disarray, yellow eyes, and a goatee. His signature attire consists of an unbuttoned pink aloha shirt, dark cargo shorts, and black geta-style sandals. Notable accessories include an inverted cross earring on his right ear and a matching necklace. He habitually places an unlit cigarette in his mouth but never lights it.

His personality is characterized by a laid-back, enigmatic demeanor and a composed disposition that rarely shows strong emotion. He prefers indirect guidance over direct intervention, emphasizing his philosophy that individuals must save themselves rather than rely on external salvation, encapsulated in his recurring catchphrase: "People can only save themselves. One person saving another is impossible." He avoids modern technology like phones and dislikes formal goodbyes, often departing locations without announcement. Despite his aloof exterior, he possesses a sense of responsibility and will intervene when balance is threatened, expressing genuine remorse if his actions lead to unforeseen consequences.

He graduated from Shinto studies in college, where he joined the Occult Research Club alongside Yozuru Kagenui, Deishuu Kaiki, Tadatsuru Teori, and Izuko Gaen. During this period, the group collaborated to create the sentient tsukumogami Yotsugi Ononoki from a century-old corpse, an act that cursed each participant. Instead of pursuing priesthood, he adopted a nomadic lifestyle, working as an oddity specialist and occasionally serving as an operative for Gaen's information network. Kaiki suggests he has no known family.

In Kizumonogatari, he intervenes to protect Koyomi Araragi from vampire hunters Dramaturgy, Episode, and Guillotine Cutter after Koyomi becomes a vampire. He orchestrates duels between Koyomi and the hunters to retrieve the limbs of the vampire Kiss-Shot Acerola-Orion Heart-Under-Blade, whose heart he had covertly stolen earlier to maintain equilibrium. He negotiates a fee but later waives it entirely when Guillotine Cutter's kidnapping of Tsubasa Hanekawa exceeds his predictions, taking personal responsibility. He brokers a compromise where Koyomi weakens Kiss-Shot to near-human levels, allowing both to coexist.

Subsequent arcs illustrate his methodology. In Hitagi Crab, he demands payment to exorcise the "heavy stone crab" possessing Hitagi Senjougahara but stresses she must resolve her emotional trauma herself; when the ritual falters, he subdues the crab physically yet allows Hitagi to achieve closure. During Mayoi Snail, he identifies Mayoi Hachikuji as a "lost cow" aberration and devises a navigational strategy to break its influence. For Suruga Monkey, he diagnoses Suruga Kanbaru's Rainy Devil arm and prepares Koyomi to confront it, refraining from direct action. He repeatedly warns Koyomi about over-reliance on his aid before departing town abruptly during the Tsubasa Cat arc.

He later reappears in Owarimonogatari after being retrieved from Antarctica by Hanekawa. During the confrontation with the entity Ougi Oshino—revealed as an extension of Koyomi's psyche—he dispels the surrounding Darkness by acknowledging Ougi as his niece, validating her existence and restoring balance, reinforcing his role as a facilitator of self-resolution.