Masaki is the wife of Isshin Kurosaki and the mother of Ichigo, Karin and Yuzu. She was murdered by a Hollow named Grand Fisher while trying to protect Ichigo.
Little is known about the life Masaki lived before marrying Isshin Kurosaki, an ex-Gotei 13 Captain-level Shinigami who had abandoned his job and The Soul Society for reasons currently unknown, and giving birth to their children Ichigo, Karin and Yuzu.
One night, while returning home with Ichigo, the two were being stalked by a powerful Hollow known as The Grand Fisher. This entity, who preyed solely on women, had turned the lure he used to draw in his prey into a little girl and made it appear as if "she" was drowning.
Ichigo, who was capable of seeing ghosts and Hollows but was incapable of distinguishing the difference between them at the time, tried to rescue the "little girl" and when Masaki realize what exactly was going on she went after Ichigo and died fending The Grand Fisher off.
According to Ichigo, Masaki was the center of their family and everything that involved their family revolved around her, and that when she died everything nearly fell into despair as the devastation caused by her loss to Ichigo led him to begin shutting himself off from the rest of the family.
It was stated by Tatsuki Arisawa that Ichigo always stopped crying whenever he saw Masaki and that she was the most beautiful mother ever.
She also stated that Ichigo had taken the blame for her death upon himself as it was he who had ran after The Grand Fisher's lure and ignited the chain reaction of events which led to her demise.
Every year since the day she died Isshin, Ichigo, Karin and Yuzu go to visit her grave and pay their respects.
It is also the only time that Isshin ever smokes a cigarette and does so in front of her grave, the reason for this being that when Isshin and Masaki first started dating she complimented on how "cool" he looked while smoking.
Aside from visiting her grave each and every year, Isshin also honors her memory with a large poster pinned to his wall that says "Masaki Forever" on it.
Masaki Kurosaki is a supporting character of the BLEACH series that was created by Tite Kubo, It first began serialization in Shueisha's Weekly Shonen Jump in August 2001. She was first seen in a picture in the first chapter, and later briefly during flashbacks in the fourth volume.
When The Kurosaki Family went to visit Masaki's grave, The Grand Fisher was attracted to the graveyard where Masaki had been buried due to their immense amount of collective spiritual energy and launched an attack against them.
He was eventually confronted by Ichigo, who remembered him from the day Masaki was murdered and used his lure to mimic her in order to break Ichigo's resolve.
However, as the fight between Ichigo and The Grand Fisher was turning in the Hollow's favor, Masaki's soul was released from The Grand Fisher's lure by force and told Ichigo her last thoughts before she had died, stating that all she was able to think about was how much fun they had together and also that she wished for Ichigo to never stop smiling.
This gave Ichigo the power to overwhelm and nearly kill The Grand Fisher, thus forcing him to flee in fear and swear revenge on Ichigo, which he would later attempt to do when he was transformed into an Arrancar by Iceringer and Di Roy Linker.
Despite all of this, Masaki's memory would not go unavenged as The Grand Fisher would meet his demise at the hands of Isshin while trying to exact his revenge on Ichigo (whose body was being inhabited by Kon at the time.)
Nevertheless, as he explained to Ryūken Ishida, Isshin still blames himself for not being able to reach Masaki and Ichigo in time to stop Grand Fisher from killing Masaki and consuming her soul.
When Hanza Nukui used his Bakkōtō, Saiga, against Ichigo in order to look into his memories Saiga and Hanza summoned Masaki, whom they had corrupted and turned against Ichigo by having her torture him with memories of her death.
Hanza then gave her the strength required for her to choke Ichigo to death and ordered her to do so knowing full well that Ichigo could never bring himself to defend himself against her.
However, before the corrupted Masaki could kill Ichigo, all of the pleasant memories they had together while Masaki was still alive emerged from deep within Ichigo and he enveloped them both in a twister of dense spiritual energy that was powerful enough to free Masaki from Hanza's control.
Ichigo then tells Masaki how much everyone misses her but that they have all been able to manage without her and are fine.
Upon hearing this Masaki smiles and then vanishes, returning to wherever it is her soul went to following her escape from The Grand Fisher's lure.
Whether that place she returned to is The Soul Society or somewhere else beyond it has yet to be revealed.
Bleach: Memories in the Rain
The 1st Bleach OVA. This is a different version of episodes 8-9, this special focuses more on Ichigo's feelings regarding his mother's death.