My Pet Slime Ate a Dragon Core and Somehow Became the Strongest Tree in the Academy

Tsubasa had been left behind by his own failure. The power training that should have raised his rank broke instead, and the academy kept him back for three years because no test could measure him right. He spent his days pruning tiny trees, watching roots, and pretending the shame did not still hurt. Then his pet slime ate a dragon core, and the quiet greenhouse life he built started to crack. The slime grew strange. The school wanted answers. Tsubasa, a middle-aged man stuck in a young body's life, had to face the fact that his skill with bonsai was the same skill he needed to survive people who wanted to use him. Someone in the academy already knew how valuable his failure had become.