Kikanshita S-Kyuu Boukensha no Quest Seikatsu

Dungeons began to suddenly appear throughout the world! Kyomi Aki became an S-Class adventurer assassin with his tremendous speed. Unfortunately, assassins were considered as a failure class. His class was becoming harder and harder to master the more he advanced. The class itself had a low attack power and mana, so he needed to always rely on someone else. One day, Aki encountered a dangerous monster that could wipe out the entirety of humanity. He somewhat managed to subjugate the monster, but lost his life in the process. Suddenly, he awoke and found himself having regressed 20 years into the past. He also received an additional “Bonus Quest” as a reward for solo killing the monster. With his knowledge from his previous lifetime and this “quest,” Aki resolved himself to redo everything to become the strongest adventurer!

A young man, Shield, can only use the beginner magic [Barrier] and has been looked down upon. Despite putting up an ironclad barrier to protect the country, he is deported due to his fiancée's tricks. However, before he knew it, he had subjugated the strongest dragon (a young girl), was courted by beautiful women from other countries, and was being followed by a group of brutal demons!?

The main character is reborn as a character from a game he played in his previous life. This character falls into ruin along with the villainess, spending the last of their years together. A man named Kururi Helan. No details of this decline is written inside the game, it can´t be understood why this sub-character ended up with the villainess route. However, that is of no importance. Living as a needy farmer along with someone is unpleasant, so the main character seeks a profession. For now, he aims for becoming a blacksmith as he originally had skill in it.