He is a hōshi (法師, ほうし, a Buddhist monk), who possesses a rather unusual curse. His right hand has a slowly expanding Kazāna (風穴, かざあな, "wind void"; "Wind Tunnel" in the English dub) that sucks in anything nearby if it's not kept covered by a cloth and strand of japa mala beads. This curse was placed on Miroku's grandfather by Naraku and passed down to him. Eventually, the curse will cause him to be sucked in as well, unless Naraku is defeated.

Miroku meets InuYasha and his friends after walking away from a town after cheating a rich man there out of some money. While bathing in a hot spring, he sees Kagome naked, also taking a bath. He discovers she has shards of the Shikon no Tama (The Jewel of the Four Souls) while staring at her breasts and takes them (the jewel shards) and her bike (which he somehow knows how to ride) with the help of his tanuki (raccoon dog spirit) friend, Hachi. InuYasha and Kagome catch up to him and InuYasha attacks him, but Miroku uses his Kazāna in return. Kagome, realizing that the monk will not harm humans, stands in its path and causes Miroku to quickly cover it with his prayer beads. Miroku explains his situation, and InuYasha reluctantly allows him to join them.

Despite his good looks and temperament, Miroku's worst vice (and best running joke) is lechery, specifically shameless flattery and occasional groping with varying subtlety. He is a big flirt that always asks seemingly single women to bear his children. This leads to him getting smacked on a regular basis by Sango. He needs to be slapped. It is notorious that he has, well, had a foster father, grandfather and father, but no trace of a mother. Miroku must have a child in order to have an heir by the time he may be killed by the curse, and thus finds it perfectly fine to offer the chance to many young women to bear his child. This later puts some strain on his blossoming relationship (which eventually culminates in a marriage proposal) with Sango, often ruining small romantic moods between them.

In fact, it was lechery that got Miroku's bloodline into trouble in the first place. His grandfather was fooled into "caring" for a young woman, who turned out to be Naraku in disguise. It was then that he received the Kazāna curse. Despite knowing this, Miroku continues his ways. As an ironic twist of fate, one episode of the anime lands Miroku in a similar situation where he woos a young woman who turns into an insectoid demon. His Kazāna suffers a dangerous rip before he destroys the demon, forcing him to seek medical attention.

Nonetheless, the monk mellows out as time goes on and proves to be a very valuable ally. He is very knowledgeable about yōkai, and is the secondary fighter of the team after InuYasha. Though quite possibly the most intelligent of the group, he often uses humor or lechery to lighten serious situations, especially if anyone is worried about him. Despite his lighthearted and lecherous exterior, it is clear he has an inner darkness (Shippō has been heard to comment that he 'never bought that holy man routine') and worries over his curse and the resulting death sentence that hangs over his head.