Kakusansei Million Arthur - Gunjou no Shugosha扩散性百万亚瑟王：群青的守护者 ; 拡散性ミリオンアーサー ―群青の守護者― ; Kaku-San-Sei Million Arthur - Gunjou no Shugosha ; Kaku-San-Sei Million Arthur - Gunjou no Sorcery Road ; Kakusansei Million Arthur - Gunjou no Sorcery Road

From MangaHelpers: In a strange twist on Arthurian legend, young Art pulls the magical sword Excalibur out of a stone--only to find himself as one of a million Arthurs, fighting to defend the island of Britain from enemies and to earn the rank of the true king. Art is pretty puny, but his childhood friend Ligu (who was also chosen by an Excalibur) tries to keep him from being immediately killed. Soon Art lives in a castle with knights, which are created beings who serve the kings. From the respect with which he treats the knights, he inspires some to hope he becomes the true king. But is that really achievable by a scrawny crybaby like him? [tethysdust]