I believe this is the first time Overlord, the extremely popular anime which finished its first season recently, has worked with an online game in Japan. Enter Nexon Japan, which started a collaboration between TalesWeaver and Overlord last week. Developed by Softmax and under Nexon now, TalesWeaver was one of those popular Asian games which never got to the English market.
For the Overlord collaboration, Ainz Ooal Gown (formerly Momonga), Albedo, and Shalltear Bloodfallen are acting as NPCs. There are new exclusive quests from the Overlord storyline, as well as monsters and bosses, which is pretty cool. From the gachapon box, players can roll special skills from Overlord, costumes (different parts), character transform potions, and even Hamsuke as a mount!