More information on Ichigo can be found on the Heroes Wiki.
BiographyEditIchigo and Orihime are in the same year at high school. They're mutual friends of Tatsuki Arisawa, but have rarely interacted before the start of the series. Sometime after Ichigo gained the powers of a Soul Reaper (a spiritual cleanser and warrior), Orihime was attacked by a Hollow (a malevolent masked spirit). Ichigo arrived in time to stop the Hollow, revelaing it to be Orihime's dead brother. Ichigo allowed Orihime and her brother to make their peace before he was purified and sent to the afterlife.
Sometime later, a swarm of Hollows invaded their town, leaving Ichigo in a difficult place as all of his friends and loved ones were at risk of being killed by them. When Orihime and Tatsuki were attacked by a Hollow, Orihime revealed her own latent spiritual powers and defeated it. She then decides to join Ichigo on his adventures.
When the Arrancar(unmasked Hollows) invade, Orihime is badly beaten, leaving Ichigo feeling guilty about not protecting her. Both resolve to improve their skills in preparation for the next assault. An Arrancar named Ulquiorra corners Orihime and threatens to kill her friends if she doesn't agree to join their side. Ulquiorra gives Orihime one night to say her farewells to the person she cares most about. Orihime sneaks into Ichigo's room while he's sleeping and confesses her love for him. She also tried kissing him in his sleep, but backed away at the last second out of shyness.When Ichigo finds out that Orihime was abducted by the Arrancar, he gathers his closest allies and launches an attack on their fortress. He gets to Orihime, only for her to be pulled out of his reach once again. Ichgio finally catches Orihime being guarded by Ulquiorra and the two duel for her freedom. Ulquiorra overpowers and kills Ichigo, causing Orihime to panic. The last thing Ichigo hears is Orihime crying, which causes his own power to corrupt and turn him into a Hollow. Hollow-Ichigo then brutally beat Ulquiorra down, the only damage he took was to his mask, which was enough to cause Ichigo to change back. Ulquiorra then dies from his injuries.
A year later, Orhime is attacked by a new enemy known as Tsukishima. He cuts Orihime, but doesn't kill her for some reason. When Ichigo finds out, Orihime tells him that Tsukishima is an old friend of hers without realising it. It is later revealed that Tsukishima has the ability to insert his prescence into someone's past and used this ability to make Orihime think he was someone she could trust. After using the same ability on everyone Ichigo knew, Ichigo decides to kill Tsukishima, only to be stopped by Orihime. When reinforcements arrive and aid Ichigo, Orihime beigns to question Tsukishima's prescence in her memories. The fact that none of it adds up in her mind causes Orihime to pass out, though she later recovers after Tsukishima is killed in battle.