Unsheathed - Chapter 206 (1): The Moon Is Round, The Moon Is Crescent

One day, Katsuragi Daichi and his classmates found themselves in a different world. The god who summoned them to another world divided its power and gave it to them, saying that it wanted Daichi and the rest to defeat the Demon King as heroes. However, Daichi alone was given no abilities. And sure enough, Daichi was thrown away and used as a decoy in a demon’s den. Eaten by a demon, Daichi had lost consciousness and thought he had passed away, though when he came to he noticed his statuses had skyrocketed. He had obtained『Revenge of the Resented』. Every time he died, his abnormal ability powered up.

In a world of magic and mystery, Mingyu, a deadly shadow assassin, seeks vengeance against the righteous Mages, who he believes are responsible for the brutal murder of his family. Consumed by his thirst for revenge, Mingyu walks a fine line between darkness and redemption.However, his path takes an unexpected turn when he encounters Jiang Yichen, a young master from one of the families he had sworn to destroy. Despite their differences, Mingyu finds himself drawn to Jiang Yichen's kindness and determination, and the two form an unlikely bond.As Mingyu becomes embroiled in the quest to unlock Jiang Yichen’s hidden potential, he begins to question his own motivations, as he realizes that there might be more to the story of his family’s demise than he initially thought.

In novels with a stud there is always a Senior Martial Brother like this:

In the early stages of the novel, his innate talent is high, his cultivation is good, his appearance is handsome, and he has an intelligent, cute younger Martial Sister as a fiancée.

In the middle stages of the novel, he is caught unprepared and defeated by a young disciple (the protagonist) in the sect who’s hardly remarkable at all. From then on, he falls from his godly altar and loses his brilliance. Even his young Martial Sister leaves him for someone else.

In the late stages of the novel, he continues to turn dark, going down the Demonic Path and becoming the major villainous boss. However, the protagonist still ruthlessly defeats him and his soul is eternally sealed.

Once Qin Mo opened his eyes, he discovered that he had become this Senior Martial Brother.

- Description from Novelupdates

After putting a suggestion to add a mercenary in a bad Murim novel he read, Leo would finish a mission with his NPCs before sleeping. Or so he planned. For some reason, he was transported into the said novel as the extra mercenary added by the author. His loyal NPCs, a yandere secretary, a happy-go-lucky assassin, a sexy puppeteer, and two weapon maniac guys start to become sentient. He lead his mercenary band ’Hallowed Insects’ toward an an unprecedented future in a Murim most turbulent era while enjoying his time. Fortunately, they still have their futuristic equipment with them. Tang Clan have a Poison Dagger, they have a Photon Sword. Shaolin Sect has a Qi Blast, they have a Railgun. And of course... “How much are you willing to pay to employ us? By the way, Demon Sect pay us 50,000 Golds to join their side in the upcoming war.” ... he always sided with the highest bidder.