This skin is available to purchase in-game, when in store rotation. The Oni Guardian is sold as a individual skin for 1775 valorant points or as a part of the Oni bundle for 7100 valorant points.
This skin is upgradable. There are different levels that changes the look of the skin, it costs 15 radianite points to unlock each level. The different variations can be seen below.
Find all the insight and weapon stats you need to know about Guardian as a gun in our weapon page.