The first few arcs of BLEACH have gone down as some of the best arcs in Shounen anime and manga. At its peak, the series came to be known as the final in a trio of golden titles that helped Jump maintain its position despite a predicted slump foreseen in the mass exodus of various hit titles that were responsible for the magazine's aptly named "Golden Age".
Shounen Jump continues to be the most popular, best-selling magazine in Japan, and what we call "The Big Three" are major titles of influence, that BLEACH emerged alongside as the major saviors of Jump. For BLEACH, the period between its serialization in 2001 and 2007 yielded some of its best arcs, with the Soul Society Arc being considered one of the best arcs from the Big Three. But why was the Soul Society Arc so special?
Death and the Strawberry
The Soul Society Arc, also called the Ryoka Invasion Arc, is the first major story line in BLEACH, and part of what makes the arc so significant is the build-up to the events that occur in the arc. The series begins by setting up the premise.
Rukia Kuchiki is the first Soul Reaper Ichigo meets in the story, and it is from the relationship that is fostered between these two that the groundwork for the Soul Society Arc is done. The first chapter and first episode of BLEACH are both titled "Death and the Strawberry", a quirky phrase that outlines what the beginning of BLEACH is really about: Ichigo Kurosaki and his intimate relationship with the supernatural.
Shinigami Substitute
When a stubborn Ichigo ends up getting in Rukia's way during their first fight with a huge Hollow, Rukia ends up paying dearly for it with very serious injuries. Rukia commits a taboo by offering her powers to Ichigo so that he could deal with the Hollow himself, and ends up gravely endangering her own life as Ichigo absorbs all of her remaining power, effectively stranding her in the human realm.
The relationship between Ichigo and Rukia begins with a level of familiarity that leads some of their classmates at Karakura High to surmise that the two are dating; however, the characters' brash sides happen to make contact on a regular basis. Despite very obvious differences, the two share a similar understanding of duty to other people, and they're both quite passionate people.
Despite everything Rukia tries to do to prevent Ichigo's further involvement in Shinigami affairs, Ichigo engages the then-6th Squad Vice Captain, Renji Abarai and Rukia's older brother, Squad Captain Byakuya Kuchiki, when they arrive to arrest her. Ichigo puts up a good fight for a fledgling Shinigami going against seated officers of the Gotei 13; however, Byakuya proves to be way too powerful.
The destruction of Ichigo's Soul Chain and Soul Sleep would have been fatal if it weren't for his composition working very hard with the dedicated medical know-how of Kisuke Urahara – the ex-Captain of the 12th Squad and founder of the Shinigami Research and Development Institute. Despite all he had gone through, Ichigo was adamant on saving Rukia because in the short time they'd been together, Rukia changed his world.
Getting the Band Together
In BLEACH, with the first major foe being the very institution of the Shinigami, the party assembly done in this first major arc is extremely nuanced and done over the course of eight volumes, which include the introductions to the various characters, their relation to Ichigo historically, their own convictions and reasons for being. Everyone had their own reasons for wanting to save Rukia, and thus, the Ichigo who was convinced that everything is his own fault and should therefore be resolved through his own power found himself saved time and time again by the various sacrifices made by his friends.
Once arriving in Soul Society, they have to then find a way to break into the Seireitei, enlisting the help of a Rukongai resident; and the unknowing relative of Ichigo, Kukaku Shiba. The Shiba Clan was one of the Five Noble Families of Soul Society alongside the Kuchiki Clan, the Shihouin Clan and two unnamed others; however, the fall of the Shiba Clan is revealed to be due to the direct actions undertaken by Rukia Kuchiki one fateful day.
Night of Wijnruit
Rukia's character arc while in captivity is one of the best BLEACH has to offer, and it gives a very startling account for many of her actions and demeanour. While imprisoned in the tower, Rukia is plagued by a vivid dream about the death of the 13th Squad Vice-Captain, Kaien Shiba, an event which turned out to be something orchestrated by Sosuke Aizen during one of his early Hollowfication experiments. In the incident, reports of Shinigami disappearing were being investigated by the then 3rd Seat of Squad 13, Miyako Shiba, Kaien's wife. She and various other operatives went on the reconnaissance mission but were wiped out by the Hollow known as Metastacia, which had the ability to take control of bodies before eating them.
Kaien also dies in combat, leaving the new recruit Rukia to have to kill her former senior and one of the few people who really accepted her. The guilt about Kaien's death drives Rukia's character immensely, as the feeling of not having been strong enough to do anything about the situation drove her into a very dark place. She blamed herself for the murder of Kaien Shiba, making herself out to be the man's executioner and nothing more, and because of her emphatic over-internalization of her guilt over her role in Kaien's death, the remaining Shiba siblings turned out to be contemptuous of the Shinigami, and their family lost its place.
Why Did You Help Me?
Understanding that Kaien's death is a huge pivot point for Rukia's character, and taking in the aforementioned proof of Ichigo's visual similarity to Kaien means that for the entirety of the BLEACH series, Rukia had effectively been looking into a face that looks just like the man she killed and feigning some level of ignorance. Rukia's lack of commentary, soliloquy or even visual proof of her reaction to seeing Ichigo's face at any point in time points towards a desire to bury that past. It is extremely noteworthy to mention that Rukia's first meeting with Ichigo led to her grievous injury during a fight with a Hollow, and as a result of her own lack of skill (her thoughts), both she and this strange boy would die.
It is possible that Rukia explaining the balance of the spiritual universe; to her springing in between a lunging Hollow and Ichigo; to giving Ichigo her power, were all products of Rukia's silent conflation of Ichigo with Kaien. Seeing "Kaien" again meant that she could finally do something to save him and protect him the way he had always protected her. It is unthinkable that Rukia's mind was not aflood with emotion at the very sight of Ichigo, not to mention his rambunctious can-do personality which is reminiscent of Kaien.
The Next Step
The introduction of BLEACH's iconic technique, the Bankai, occurs in the Soul Society arc, during Yoruichi Shihouin's training of Ichigo. Ichigo approaches the tower where Rukia is held but between himself and victory is Byakuya Kuchiki. Ganju is incapacitated in the conflict, but before things can go too far, Yoruichi knocks out Ichigo and requests that Byakuya give her three days to make Ichigo stronger than he is.
Th Soul Society arc is important because it highlights the impressive technological and combat prowess of Yoruichi and her companion Urahara, and the sheer ball of combat potential that is Ichigo Kurosaki. Bankai, the Second Release of the Shinigami's weapon of choice, the Zanpakuto (Viz. "Soul Slayer"), is introduced as the kind of high-level technique achieved by only the most talented Shinigami after training for several years on end. It is comparable to Goku performing the Kamehameha minutes after observing it for the first time, albeit the stakes are much higher for Ichigo in the situation.
As Aizen Has Planned
The Soul Society Arc saw the emergence of one of the most iconic anime villains. The antagonist of the Soul Society Arc turns out to be Sosuke Aizen, who in true Machiavellan fashion, faked his own death and murdered the central governing unit of the Seireitei's affairs to orchestrate all decisions made by the Gotei 13, including Rukia's execution. Rukia's execution was to be performed by the sacred blade known as the Soukyoku, a powerful mass of Zanpakuto capable of smiting one's soul from existence. Rukia's temporary human body (Gigai), unbeknownst to her, was the hiding place of a certain device which had the ability to dissolve the line between Shinigami and Hollow.
The Hougyoku is one of the most powerful objects in the BLEACH universe as it is revealed to be one of two that exist. The first was made by Aizen, the second invented by Kisuke Urahara; which Aizen steals from Rukia's soul and takes it with him to Hueco Mundo. Overall, the Soul Society Arc's amazing plotline, use of characters and their development, as well as the unveiling of the true antagonist, Aizen, is what led to it being so well received, and it goes down as one of the BLEACH franchise's greatest arcs.