Episode 161

Miroku's Past Mistake is the one hundred sixty episode of the InuYasha anime.

Summary
Inuyasha, Kagome, Miroku and Sango are walking along a trail and Miroku is seemingly upset over getting pick-pocketed by a man. But, instead, he uses his supposed upsetness to stroke Sango's bottom in a hug. (This is noted to be the first, and only, time he's actually gotten away with groping her since Sango does nothing to stop him, just simply saying, "Miroku..." and closing her eyes as she blushes while he is doing it).

Some villagers place a charm on a shrine, praying that the soul will find peace. As they do, the ground shakes and the water roils.

As Inuyasha and companions arrive to offer help, one of the villagers recognizes Miroku and asks if he has returned to fulfill his promise and marry his daughter, shocking everyone since Miroku is engaged to Sango.

In the village, Miroku is unable to recall the promise at first. However when a young lady arrives, the memory seems to return when he recognizes the girl from his past. The girl, Shima, used to be sickly and frail. But as he passed through the village one day he healed the girl and left - after making his usual proposition to the girl. Shima claims that the medicine as well as her promise to Miroku is what kept her going. These events soon cause a great strain on Miroku and Sango's relationship as Sango becomes further and further upset now fully taking in Miroku's womanizing past.

The villagers tell the companions that the water demon who lives in the shrine, the Master of the Lake, has claimed Shima as his bride and refuses to give her up. Shima's father explains that he had promised Shima to the Master of the Lake using his sources to cure her during her illness. Shima then confesses to the Master of the Lake while in a confrontation with the water demon as well to her parents and the group one night that she is not a virgin saying that she had slept with Miroku and gave her virginity to him (causing Sango to be silently enraged upon hearing this) and thus is unfit as a bride. The Master of the Lake, furious that that he had been lied to, soon transforms and attacks the village. Sango also rejects Miroku, saying that she doesn't think things will work out between them after, all while Inuyasha attacks the demon which she seems to not be fazed by, stunning Miroku that she is ending their engagement.

Miroku tries to explain things to her asking if he could even give his side of the story, but Sango runs off clearly distressed and Miroku is left gut wrenched that she doesn't trust him. Miroku soon reveals to Inuyasha, Kagome and Shippo that he had actually been falsely accused of the things he had supposedly done with Shima and that his heart "was focused on one person and one person alone." (This being Sango.) While they are distracted, the master of the lake kidnaps Shima.

Sango rescues Shima from the demon, but is caught by the demon. When the demon gloats that he shall keep Sango as his mistress, Miroku leaps into the lake after them declaring that no one will go after "his woman," and declaring Sango his and his alone, clearly shocking Sango. Miroku then uses his Wind Tunnel to remove all the water from the lake and defeats the demon. However after the defeat of the demon, Sango walks away from Miroku. Miroku chases after her and as she continues walking away, she smiles to herself, which Miroku sees and smiles as well as he continues chasing after her as the others watch from nearby.

Shima soon confesses that she lied about sleeping with Miroku, resulting in Sango and Miroku patching things up and finally smoothing things over with each other.