Death March kara Hajimaru Isekai Kyusoukyoku (WN) - Book 16 - 16-51. Guardian Dragon

Lingyun, a fierce and savage cultivation genius takes over a dead teenager’s body. Coincidentally, they are both named Lingyun. Set in a alternate version of the 21st century, teenager Lingyun has been killed by someone with a grudge.

- Description from Novelupdates

In a world of magic, monsters, and rising heroes…A quiet young man with a simple life finds himself walking a path far greater than he ever expected. With his axe in hand and peace in his heart, he'll discover strength where others seek power.Slow-burn growthParty bonds & adventureUnique class & stat systemA journey that starts small—but won’t stay that waySometimes the strongest warriors are the ones who never wanted to fight.

Vincent Strider was a gun for hire who made a living by killing whoever it was his clients wanted dead. But during one mission, he died in a fierce gunfight. However, death was not the end for him. Vincent found himself reincarnated in another world, facing a floating interface that flickered before his eyes.[Synchronizing Host!][Military System initializing.]Vincent found out that in this system he received, he can summon soldiers, tanks, aircrafts, and even warships! This is going to be exhilarating.