1. Tenzō Threatens Itachi: Tenzō, also known as Danzō, holds a high position in Konoha but lacks the authority to give orders to Itachi. However, internal conflicts within Konoha lead Tenzō to threaten Itachi and manipulate him into carrying out a mission that creates a tragedy. This could have been avoided if Tenzō had better managed the conflict between the Uchiha Clan and Konoha.
2. Itachi's Hatred towards Tenzō: Itachi, operating under the guise of Kakashi, knows Tenzō's true identity as the hidden leader of the Akatsuki. Itachi also knows Tenzō's dangerous nature and accepts his orders only to prevent a war. As someone who values peace, Itachi must harbor deep hatred towards Tenzō.
3. Orochimaru, Itachi's First Partner: Orochimaru, Itachi's initial partner in the Akatsuki, is more experienced and knowledgeable, but his weaknesses align with Itachi's strengths. Despite Orochimaru's desire to take over Itachi's body, he is no match for Itachi. Orochimaru's betrayal and targeting of Itachi's younger brother, Sasuke, fuel Itachi's hatred towards him.
4. Kabuto's Assistance: Kabuto, following in Orochimaru's footsteps, aids Tenzō in initiating the Fourth Great Ninja War. Without Kabuto's help, Tenzō may not have been able to defeat the Shinobi Allied Forces. Itachi's Izanami ability proves crucial in the battle, while White Zetsu's abilities alone would not have been effective.
5. Deidara's Grudge: Initially, Deidara has no personal vendetta against Itachi. However, after being defeated by Itachi's genjutsu during his recruitment into the Akatsuki, Deidara holds a grudge. This hatred extends to Sasuke, and he nearly kills Sasuke during their confrontation. Itachi naturally despises someone who harbors ill will towards his brother.