I felt the need to make this analysis because I've read how much Rin fans hate Kagura and vice-versa.
This analysis is unbiased and has points that both sides have yet to think about. This will decide who Sesshomaru's canon "romantic interest" is.
There are three females for Sesshomaru: Sara Asano, Kagura, and Rin. One thing they all have in common: They've all died. Rin died twice but revived.
Sara Asano
She is an anime exclusive character who isn't that significant to argue for or against.
Kagura
At first, Sesshōmaru appeared to be annoyed with Kagura's constant appearances because he felt as though he had no obligation to be "used" to fight Naraku so that she could be free.
After being injured by Goryōmaru's light cannons, she falls into a river near Sesshōmaru. Initially, he rejects Jaken and Rin's proposal of helping her but after both of his companions fall into the water in an attempt to save her, he saves all three of them.
Her feelings for him are one-sided.
She died.
She is an incarnation of Naraku. She would have died anyway should Naraku be destroyed, proven by Byakuya. Did she know? Probably. Did he know? No. Kagura's life is linked to Naraku. She cannot live without him and will die when he does.
While Kagura caused Tenseiga to be reforged, it was Rin's death that further powered up Meidō Zangetsuha.
He defended her honor. Nothing more, nothing less.
Rin
She is the most important person to both Sesshōmaru's character and life. He goes out of his way to save her and protect her.
Did they have a guardian/ward relationship? I'd say so. In the future, there's a good chance Rin'll be more than just a ward.
Sesshōmaru has TWO primary objectives throughout the series. 1. Protect Rin. 2. Destroy Naraku. I might add, in that order. Sesshōmaru refused to destroy Naraku until Rin was safe.
If Tenseiga never convinced Sesshōmaru to revive Rin, he would remain a heartless cold villain rather than an anti-hero. She was the source of his character development.
Sesshōmaru went to the deepest parts of the Underworld to save Rin only to realize that he couldn't and that was the most emotion he's shown all series. "Nothing was worth losing her. Nothing at all."
He was much happier when his mother revived Rin.
He spoils her in the epilogue. In feudal Japan, giving a girl kimonos is a form of courtship.
She admires him. DOES NOT love him…yet.
She's alive. Once revived by Sesshōmaru and the second time by his mother.
Sesshōmaru's mother has made the comment that Sesshōmaru is more becoming like his father because he cares for humans now.
Naraku knows Rin is Sesshōmaru's weakness. Jakotsu and Byakuya too.
InuYasha's gang knows Rin is the most important life to Sesshōmaru and will avoid hurting her. Also, none of them would ever hurt an innocent child.
Rin is the closest female character to Sesshōmaru. He cares more about Rin than he gets along with his own mother. That's why we only see her once.
Rin is the only character (from the entire series) that Sesshōmaru will never harm or be rude to.
The mention of her name can snap Sesshōmaru out of his anger (red eyes).
If you can find the InuYasha one-shot manga titled "After That", you will find Sesshōmaru at Kaede's village. He goes there ONLY to protect Rin while everyone else is fighting some demon.
Even someone as annoying as Jaken knows Rin is Sesshōmaru's priority.
Sesshōmaru only tolerates other characters when they mean Rin well.
Sesshōmaru's and InuYasha's father's true love was a human. InuYasha truly loved two human women. There is a good chance that Sesshōmaru's future love is Rin who is also human.
Sesshōmaru can tell the difference between the real Rin and an illusion.
Rin in the first and only human character shown in the series to be revived by Tenseiga.
You will never find Sesshōmaru looking at any female the way he looks at Rin.
In an official Drama CD (content approved by Takahashi herself), Kagome and InuYasha are listening to a recording of Sesshōmaru's would-be proposal to Rin. Hear/read it here: inu-drama. tumblr /post/58964960640/asatte-05. He is willing to wait until Rin gets older to begin a relationship.
In a previous track to the one mentioned above, Jaken quickly concludes that Sesshōmaru intends to ask Rin to live with him as his bride. Sesshōmaru even goes to his father's grave for some ideas/advice.
In conclusion, Kagura is NOT Sesshoumaru's canon romantic interest.
