Kindan Shitei de Breakthrough: Boy Meets Satan  

A Breakthrough Came Out by Forbidden Master and Disciple., A Breakthrough Brought by Forbidden Master and Disciple, 禁断師弟でブレイクスルー～ボーイ・ミーツ・サタン～, 禁断師弟でブレイクスルー~ボーイ・ミーツ・サタン~

It seems that Eirth, the son of a hero who defeated the Great Demon King, is struggling to live up to his father's legacy. Despite putting in great effort and achieving impressive results, he feels like he falls short of expectations. This has led to feelings of disappointment and frustration towards himself and others. It appears that Eirth has been receiving personalized training from the ghost of the Demon King, who is now serving as his mentor. The purpose of this training may be to help Eirth overcome his struggles and prove himself worthy of his father's legacy. In the coming days, it seems that Eirth will face significant challenges, including confronting his parents, first love, childhood friend, geniuses of the era, and the world itself. It remains to be seen whether he will rise to these challenges and become a hero in his own right or continue to struggle with feelings of inadequacy.