Bleach: Getting Stronger Starting from Teaching at the Spiritual Arts Academy

Shikatoshi Nanatsuki is transported to the world of Bleach and becomes the younger brother of the first captain, Shikatoshi Hakunsai.
He thought he had a powerful patron to rely on, but he discovered that Lu Quba Yunzhai was terminally ill and only had a few years left to live.
Fortunately, he awakened the teacher system, which allows him to become stronger by teaching.
In order to gain the strength to stand on his own in this world, Shikatri Nanatsuki became a teacher at the Spirit Arts Academy and inherited the Shikatri Dojo, working hard to teach and mentor students.
[Kensei Rokusha completes his swordsmanship training under your guidance and receives the reward - Sword Skill: Crimson Tide]
[Under your guidance, Aizen Sousuke completed his Kido training and received the reward—Hado No. 90: Black Coffin]
[Under your guidance, Ichigo Kurosaki's strength has greatly increased, and he has received a reward—the Holy Symbol: D]
Years later, Aizen Sousuke suddenly came to his door:
"The void of the Throne of Heaven has lasted too long. Please, teacher, step in and end this unbearable void!"
"From this day forward, teachers will stand at the top!"
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(This book is also known as: I Taught Swordsmanship in Soul Society, My Disciples Led Me to the Soul King Palace, and I Became the Lord of the Four Realms Starting by Teaching Swordsmanship)