Kurosaki Ichigo is a teenager gifted with the ability to see spirits. His life is drastically changed by the sudden appearance of a Shinigami (literally, Death god) - one who governs the flow of souls between the human world and the afterlife - named Kuchiki Rukia, who arrives in search of a Hollow, a dangerous lost soul. When Rukia is severely wounded while trying to defeat the Hollow, she attempts to transfer half of her Reiatsu (literally, Spiritual pressure) energy to Ichigo so that he can defeat the Hollow. However, Ichigo takes almost all of her energy, transforming into a Shinigami and allowing him to defeat the Hollow with ease. With her powers diminished, Rukia is left stranded in the human world until she can recover her strength. In the meantime, Ichigo must take over Rukia's role as a Shinigami, battling Hollows and guiding souls to the afterlife realm known as the Soul Society.

[Source: Wikipedia via AniDB]

Kurosaki Ichigo, the temporary Shinigami(Death God) for Kuchiki Rukia, discovers his mother's killer as one of the Hollows he has been hunting. He does battle with it in a prideful battle of revenge. This Special is actually a flashback of previous episodes in Bleach. After the ending credits, a short plays showing Shinigami and their Zanpakutos to "Number One" from the Bleach Soundtrack.

A Shinigami named Baishin who was sealed by Soul Society long ago is set free on Earth. On a fateful day Ichigo encounters him and has roughly half of his reiatsu drained. Its now up to Ichigo and the Soul Society to finally put a stop to Baishin and his destruction.

In Karakura Town, there has been a sudden outbreak of unidentifiable spirits called "blanks" (vacant souls) while in the skies of Soul Society, the real world has been reflected. A mysterious female shinigami called Senna has appeared before Ichigo along with a man named Ganryu, leading a group called the "Dark Ones."

[Source: Anime News Network]

A valuable artifact known as "King's Seal" is stolen by a mysterious group of people during transport in Soul Society. Hitsugaya Toushiro, the 10th division captain of Gotei 13, who is assigned to transport the seal fights the leader of the group and shortly after goes missing. After the incident, Seireitei declares Hitsugaya a traitor and orders the capture and execution of Hitsugaya. Kurosaki Ichigo refuses to believe this, and along with Matsumoto Rangiku, Kuchiki Rukia and Abarai Renji swear to uncover the real mastermind of the stolen seal, find Hitsugaya and clear his name. Meanwhile, a rogue Hitsugaya searches for the perpetrators and uncovers a dark secret regarding a long dead shinigami.

[Source: Anime News Network]

An animated adaptation of several chapters of Colourful Bleach.

A mysterious reiatsu (spiritual particle) explosion occurs in the center of Seireitei in Soul Society, causing it to be destroyed. At the exact same time, a major change overwhelms Rukia Kuchiki, which leaves her losing something important inside. Kisuke Urahara sends Ichigo Kurosaki to Soul Society to investigate the disturbance. Upon reaching Seireitei, Ichigo is set upon and attacked by shinigamis, once allies, who have no memory of him and Rukia. Now alone and on the run, Ichigo must find the missing Rukia and uncover the cause of the mysterious incident before it's too late.

[Source: Anime News Network]

Hell–A place where beings that have committed mortal sins during their lifetime are sent. It is a realm where even Soul Reapers are forbidden to interfere. When a group of vicious Sinners plot to escape from this eternal prison, they discover that Substitute Soul Reaper Ichigo Kurosaki is the key to their freedom.

[Source: VIZ; emended]

Was it all just a coincidence, or was it inevitable?

Ichigo Kurosaki gained the powers of a Soul Reaper through a chance encounter. As a Substitute Soul Reaper, Ichigo became caught in the turmoil of the Soul Society, a place where deceased souls gather. But with help from his friends, Ichigo overcame every challenge to become even stronger.

When new Soul Reapers and a new enemy appear in his hometown of Karakura, Ichigo jumps back into the battlefield with his Zanpakuto to help those in need. Meanwhile, the Soul Society is observing a sudden surge in the number of Hollows being destroyed in the World of the Living. They also receive separate reports of residents in the Rukon District having gone missing. Finally, the Seireitei, home of the Soul Reapers, comes under attack by a group calling themselves the Wandenreich.

Led by Yhwach, the father of all Quincies, the Wandenreich declare war against the Soul Reapers with the following message: “Five days from now, the Soul Society will be annihilated by the Wandenreich.”

The history and truth kept hidden by the Soul Reapers for a thousand long years is finally brought to light.

All things must come to an end—as Ichigo Kurosaki’s final battle begins!

[Source: VIZ]

Part 3 of BLEACH: Thousand-Year Blood War.