Younger Sister Training System – My Younger Sister’s Growth Is the Key to for Me to Become the Strongest in the Other World!

Ren Tsukishiro, an ordinary university student, found himself reincarnated in another world. There, he encounters his lovely younger sister, Lilia Sylphid. The mysterious system recognises her as his ‘younger sister’, without her growth, he cannot grow up either. As he struggles to make his sister smile, he gradually becomes the most powerful being in the world. However, why was the system so obsessed with the growth of his younger sister? A vital secret lies hidden that could shake this different world – In order to become the strongest, there’s no other choice but to train a younger sister