The Ten Thousand Clans Invasion: Guardian of the Rear is a Manga/Manhwa/Manhua in english language, Action series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

“Invasion of the Ten Thousand Clans, universal superpowers, the era beyond time has arrived! In this age, all citizens are drafted to resist the foreign races and defend against external humiliation. Nan Ziying, at the tender age of adulthood, chooses to stay behind at the recruitment center, serving as logistical support. Many soldiers are disappointed, the youth scorn him, and white-haired elders take up arms and leave, leaving him behind with only women, children, and the elderly to guard the rear. Later, Nan Ziying awakens five great abilities and silently prepares. In this era where countless clans reign supreme and the times are filled with tragic heroism, ‘I am the calamity of these ten thousand clans!'”