Tite Kubo's popular manga series Bleach spawned a popular anime series of the same name, and this juggernaut fantasy action story was quickly recognized as one of shonen's "big three." Despite its numerous action scenes and impressive powers, very few Bleach heroes or "good guys" perish in the storyline. It is usually the villains who die.
Even though heroes are significantly more likely to survive and prevail than villains in any work of fiction, Bleach's tale appears to be quite hesitant to kill off any heroes over its several story cycles. Unless viewers count Central 46's massacre off-screen, no one died during the Soul Society arc, for instance. Even still, Bleach has emotional impact and some stakes, so occasionally, the heroes do actually perish.
Yachiru/Retsu Unohana was killed while fighting Kenpachi
For centuries, Captain Retsu Unohana was known as a soft-spoken but strong-willed Soul Reaper who had a motherly air about her, and she could intimidate any troublemaker with a glance. That's how Ichigo knew her too, but in the Thousand-Year Blood War arc, Captain Unohana's true nature emerged. She had once been Yachiru Unohana, the first Kenpachi and first Captain of squad 11. She had found and recruited a young Kenpachi Zaraki, and now, the time had come for their final duel.
Only one of them could survive, and Yachiru pushed Kenpachi to the limit to help him realize his true power. She gladly gave her life so her protege could unlock his shikai, Nozarashi, and become who he was meant to be. It paid off, but Kenpachi cried out in despair, unwilling to lose his old mentor and role model in the process. Yachiru found that rather amusing as she died.
The Soul King received a life-size reward from Captain Jushiro Ukitake
As a boy in the Rukongai district, Jushiro Ukitake nearly died of an illness until the right hand of the lofty Soul King, known as Mimihagi, intervened. Mimihagi saved Jushiro's life, allowing him to grow up and train as one of the first-generation Soul Reapers under Yamamoto. He easily survived most of Bleach's story arcs even when facing foes such as Coyote Starrk, but when the Quincy king Yhwach threatened the Soul King, Ukitake took drastic steps to save the Soul King.
Ukitake willingly gave back the life he had been given. At great cost, he helped slow down Yhwach's plans, giving Ichigo and the others another chance to save the world. Squad 13 was left without a Captain, so once the war was over, Rukia Kuchiki replaced Ukitake as Captain, and she still holds that rank as of the recent Bleach one-shot chapter.
Masaki Kurosaki was killed when Grand Fisher attacked him
After Yamamoto passed away, experienced Soul Reaper Shunsui Kyoraku assumed command of Squad 1, and the Soul Reapers had to find a means to fight the Wandenreich without Yamamoto's overwhelming might and knowledge. The stakes were higher than ever before when his death made the strength of the Wandenreich even more apparent.
The tragic loss of Ichigo's mother was shown early in the story, but the full details weren't revealed to Ichigo and the viewers until partway through the Thousand-Year Blood War arc, when Isshin explained all this to Ichigo. It made the fight against Yhwach that much more personal.
Fighting Yhwach once more, Captain Yamamoto perished
Captain-General Yamamoto appeared to be invincible for centuries, but he died early in the TYBW story arc, which had a profound impact on the Soul Society. Yamamoto made the mistake of not killing a younger Yhwach a thousand years ago, and it came back to haunt him. Yamamoto's Lieutenant Sasakibe was the first to be killed. Yamamoto then died while fighting his old Quincy foe, and Yhwach humiliated him before obliterating his body with arrows.
Yamamoto's death forced veteran Soul Reaper Shunsui Kyoraku to take over as Squad 1's commander, and the Soul Reapers would have to find a way to defeat the Wandenreich without Yamamoto's formidable power and expertise. His death highlighted the Wandenreich's power, and the stakes became higher than ever before.
Notably, Yamamoto ended up in Hell along with Unohana, since they both had such dense and powerful spirit energy, and their presence in Hell is what allowed Hell's doors to open from the inside in the new one-shot. Even in death, Yamamoto is still shaping the world around him in big ways.
