Mahou no Kuni no Madan

Karito Watari is a veteran player of a Military Shooting VRMMORPG. The place which he wandered into was another world of swords, magic and gambling. What awaited him there was a demi-human sister and a battlefield full of malice. If one wants to survive, if one wants to protect, he will need to use all means.

(Source: Novel Updates, edited)