[Manga] The Brothers' Conflict (Tsugai)

Born as twins dividing night and day, Yur and Asa were separated when they came of age. Yur lived unaware of this fact, raised by Grandma Yamah, until one day mysterious attackers appeared in the village. Eventually, Yur leaves the village, gradually uncovering the secrets hidden within his family and village. Meanwhile, Asa also moves towards his own goals, and the conflict between various forces surrounding the two begins. Yur and Asa pursue the truth in their own ways, in different places. This work is still ongoing, with 12 volumes published so far. It's by Hiromu Arakawa, famous for Fullmetal Alchemist. The first season of the anime has concluded, and it has been officially announced that a second season will be produced. The anime is made by the same team that produced FMA, so the direction is absolutely insane (purely subjective). The manga is also incredibly enjoyable, with both the art and story being top-notch. Overall, I'd say you'd be missing out if you don't read it. I highly recommend this to anyone who enjoys action series.