Steel Angel Kurumi follows the story of a young boy named Nakahito Kagura. He is pushed by a group of classmates to go into a house rumored to belong to a mad scientist named Tetsuo Ayanakouji. Inside, he comes across what seems to be a lifelike doll. At the same time, the Japanese Army carries out an attack on the house. During the attack the "doll" falls over and Nakahito accidentally kisses it, causing it to awaken. The doll turns out to be the Steel Angel Kurumi, who is being hunted by the military for mysterious reasons.
After being awakened by Nakahito's kiss, Kurumi immediately becomes possessive of him while simultaneously pledging her love and service to him. An incredibly wild individual, she is overwhelmingly manic when it comes to Nakahito, whom she calls "Master". After escaping from the army and hiding at Nakahito’s family shrine, The General of the army, along with Reiko Amagi and the mysterious Dr. Brandow, managed to find and forced activate Saki, another Steel Angel with orders to destroy Kurumi and seize her Mark II Heart. Saki and Kurumi fight with Kurumi being defeated easily due to Nakahito's still-standing order to not fight. The victory is short-lived however, as Saki's improper activation causes her to collapse. Kurumi kisses Saki, and her Mark II Heart re-energizes Saki's Angel Heart. The action permanently activates Saki, and the master-servant relationship is reinstated, with Saki pledging her loyalty and love to Kurumi. Kurumi largely ignores this vow, but the two mutually call each other "sister" from then on. The scene is short lived as Dr. Brandow wounds and kidnaps Dr. Ayanakouji and disappears.
Realizing that a secret third player was in the mix, The General gives Amagi a discharge from the army so she can investigate Brandow without causing an international incident. She convinces Nakahito, Kurumi and Saki to join her on her journey to find Ayanakouji’s lab. While on their trip, The General sent Yoshino Koganei and Eiko Kichijoji to watch over and covertly aid the Steel Angels. As the story continues, the group is attacked by other Steel Angels sent by the organization that kidnapped Ayanakouji, which was called the Academy. Also following them is another Steel Angel called Karinka. Karinka was activated by the Academy to destroy Kurumi. She is very strong due to being installed with two Angel Hearts instead of one, however this also means she is exempted from following the orders of Dr. Walski, her creator. She later joins Nakahito and the group, originally to figure out Kurumi’s power, but she eventually develops a crush on Nakahito. It was thanks to Nakahito that Karinka became friendly.
After finding Ayanakouji’s lab, Nakahito was kidnapped by the Academy in hopes of luring Kurumi to them. During the attack on the Academy, Kurumi underwent a change and incased herself in a shell that the Academy could not break, which led to both sides to join together to stop Kurumi. During the truce, Nakahito learned that Dr. Ayanakouji, Brandow, and Walski were from the future and traveled to the past to conduct an experiment with the Steel Angels. But somewhere during their experiment, Ayanakouji left them to further his research thus causing the events as they unfolded. After their meeting, they agree that the evil in Kurumi’s broken heart would have to be destroyed even If it meant destroying her as well. During their final strike, Nakahito managed to enter Kurumi shell and purified her heart with his kiss thus returning everything to normal.
The story of Steel Angel Kurumi continues in a second series. The story takes place back at the Kagura Shrine, in AD 200X, about 4 generations after Nakahito Kagura. One day, Nako Kagura and her best friend Uruka get lost in the shrine's basement labyrinth and run across a dog and a giant, scary, flying statue. As Nako and Uruka run away from the scary flying statue, Nako trips and is caught by the statue, which covers her in a divine light. She is then given a message by Dr. Ayanakouji through the statue, the statue then breaks apart and out falls Kurumi, right onto Nako's lips. Again, the events come full circle, and Kurumi awakens from a new master's kiss. Now being the receiver of the same affection that was given to her great ancestor Nakahito, Nako is constantly chased and protected by Kurumi.
Uruka is in love with Nako, and had originally hoped to be the one to take Nako's first kiss. On the day that Kurumi appeared, she was the first witness to see the fateful kiss, to which she could not get over for an entire day. Uruka now sees Kurumi as an obstacle to Nako and will try anything to remove Kurumi, even if it means asking her father to call upon the family's private army to take her down. When they find that Saki is a Steel Angel, the family army decides to use her as a weapon against Kurumi, the "source of Uruka-chan's unhappiness." On the day that Saki was to be awakened, Uruka was there to supervise the process, but got involved in a fantasy of her own, involving Nako, and ended up kissing Saki. Saki then falls in love with her new master, and Uruka wants nothing to do with her.
Of course in this story, Karinka makes an appearance and like in the first series, Karinka gets a crush on whomever Kurumi loves, and Nako becomes victim to another suitor. During the second story, Nako would say that her life sucks but in the end, she says that it now really rules.
Of course in this story, Karinka makes an appearance and like in the first series, Karinka gets a crush on whomever Kurumi loves, and Nako becomes victim to another suitor. During the second story, Nako would say that her life sucks but in the end, she says that it now really rules.