Ichigo Kurosaki vs. Renji Abarai & Byakuya Kuchiki

Ichigo Kurosaki vs. Renji Abarai an Byakuya Kuchiki is the first fight between Ichigo and another Shinigami. It takes place in the "Substitute Shinigami" portion of the Shinigami Saga.

Realizing Soul Society would soon come after her, Rukia flees the Kurosaki Clinic, attempting to keep the heat off of Ichigo. When Ichigo learns of this he leaves immediately to try and stop her. Meanwhile Rukia is spotted by two Shinigami: Captain Byakuya Kuchiki, Rukia's adoptive older brother, and Lieutenant Renji Abarai of the 6th Division. Uryū Ishida, who followed Rukia, intervenes to protect the unarmed Rukia, but is promptly dispatched by Renji.

Battle
Ichigo arrives at the scene just in time to stop Renji from landing a finishing hit on Uryū, catching him by surprise. Renji backs away to take a better look at the person who blocked him. Ichigo represents himself, saying he will defeat Renji. Seeing a Shinigami before him, Renji is baffled for a minute, but quickly recovers and connects the dots. Realizing Ichigo is the human to whom Rukia gave her powers, Renji attacks. Ichigo soon finds himself on the defensive. Renji mocks Ichigo's abnormally large Zanpakutō and soon manages to slice deep into Ichigo's shoulder. Ichigo falls to his knees as Renji tells him that Rukia, after regaining her powers, will be taken to Soul Society and executed. Renji boasts that Ichigo could never even scratch an experienced Shinigami like himself. This aggravates Ichigo, who responds with a sucker attack that scratches Renji's chin.

Byakuya intervenes for the first time, telling Renji he's been careless. Renji protests but Byakuya says Ichigo was responsible for the wounding of a Menos Grande two days before. Renji laughs in disbelief, disregarding the report, he asks Ichigo for the name of his Zanpakutō, which of course, Ichigo doesn't know. Renji then releases his Zanpakutō and reveals his Shikai, Zabimaru, explaining a Zanpakutō can change its shape and size in accordance with its wielder's spiritual power, telling ichigo he should return once he's trained for 2000 years.

Renji attacks again, this time with a revealed Shikai. Ichigo attempts to block but is sliced badly in the shoulder by Zabimaru. Renji once again is about to administer a killing blow and once again is thwarted, this time by Rukia, who jumps on his back and cries for Ichigo to run away. Instead of running Ichigo grabs the hilt of his sword and stands up to face Renji again.

Ichigo suddenly experiences an increase of his Reishi, noted also by the Shinigami surrounding him. Before Renji has a chance to react, Ichigo slices through his shoulder, then turns around and attacks again, breaking Renji's sunglasses and leaving a gash in his forehead. Unbeknownst to Ichigo, his speed has increased. Feeling his renewed Reishi like a surge of energy, Ichigo attacks the shocked Renji, intending to finish the fight. The attack fails to connect. Looking at his sword, Ichigo suddenly sees it only has about 15 cm (6 in) of blade left. Realizing Renji couldn't have done it, Ichigo looks at Byakuya, standing where he stood since the begining of the fight, holding the rest of the blade in his hand. He then drops the blade and appears suddenly next to Ichigo while a huge amount of blood sprays out of Ichigo's chest.

Ichigo crumples to the ground. Rukia rushes to his side but is apprehended by Renji. Renji tells her she shouldn't aggravate her sentence by helping Ichigo any further, but she insists that she must as it is her fault that he is dying. Byakuya hears this and remarks that Ichigo bears a striking resemblance to him. Ichigo reaches and grabs Byakuya's uniform. Everyone is surprised to learn that Ichigo is still alive and conscious. Byakuya orders ichigo to let go, but Ichigo refuses. When Byakuya threatens to cut his hand off Rukia rushes to kick Ichigo's hand away. She tells Ichigo to know his place and calls for her brother to leave in light of Ichigo's crude behavior.

Ichigo tries to get up but Renji stomps on his back and suggests he lies there quietly and dies. Rukia says to her brother not to bother killing Ichigo, since he would probably die on his own. When Ichigo tries to stand up again she tells him to stay put, and that if he should try to follow her, she would never forgive him. Byakuya agrees to leave Ichigo there, saying his attack, which cut through Ichigo's Saketsu and Hakusui, took away any trace of Shinigami power, even if he should live. To Byakuya's order, Renji opens the Senkaimon and the three Shinigami depart to Soul Society.

Aftermath
Ichigo's life is saved by Kisuke Urahara, but he is forced to go through rigorous training in order to access his latent Shinigami powers which were awakened by Rukia's intervention. He also makes contact with his Zanpakutō for the first time and learns its name and the name of its main attack. Rukia is taken back to Soul Society, where she is sentenced to be executed by the Sōkyoku. Uryū, Chad and Orihime also train with the intent to accompany Ichigo in his quest to save Rukia's life.