Shangri-La Frontier 4

Fresh from hours of level grinding, Sunraku embarks on a quest with fellow gamers Pencilgon and OiKatzo to defeat Wethermon the Tombguard, one of the mighty Seven Colossi. Pencilgon introduces them to an NPC known as Setsuna of Bygone Days, who begs them to put Wethermon's soul to rest. Though the three friends vow to fulfill Setsuna's wish, the undead swordsman will prove more terrifying than they could ever imagine.

Volume 4 of the Shangri-La Frontier manga series by Ryosuke Fuji.