This one is one of the heavily developed Lunarik (There are like 90 heavily developed ones, not counting Ril. The rest are also rather developed but aren't set in stone and have room for adaptation so I can adapt them as needed for plot/sidequests/interactions and heavily develop them at that point.) it just happens to pair extremely well with your character and will function partly along those lines..
Powerlevels, in terms of pure combat, a single Lunarik under the full moon can take down over a dozen Eastern Trolls with effectively no injury due to their regeneration(The type that regenerates and are massive and absurdly strong.) In terms of magical ability Lunarik are hopeless since they cannot channel magic, although they do have a few minor magic related innate traits, such as their regeneration and their ability to smell auras, although it isn't exactly common knowledge among Lunarik that it is auras that they smell, they just assume it is the person's natural scent. (As was hinted at by Rilae's reaction to both Lyeos's and Zal's character's scents.). In terms of stealth and general thiefness, they are rather good at it. Lunarik start extremely potent and begin slowing down at age ten, they plateau at about age twenty and will only learn more with age. They have an extremely hard time forgetting anything, they can't repress bad memories and they often have too many bits of knowledge flying around in their heads, their mind takes in data and never lets it out. Most Lunarik die by age 40 due to discharges, although it is in theory possible for them to live forever, it's just extremely rare if they don't have some sort of permanent way to stabilize their mind and emotions. Their personality gets less hyper with age and more contemplative, although normally they stay rather energetic. In terms of power ranking, Lunarik start rather powerful but also have many downsides to their power. Sort of like fireworks, they streak into the night sky, glowing brightly with energy before bursting into a spectacular explosion.
Kitsune are more illusionbased then anything else, so they are rather good with thiefy things since illusions make it a bit hard to notice something without magic detection. Magicwise, they are average outside of illusion magic, although many specialize in one or two specific types (Like your Kitsune and shadows.) Physical combatwise, they are fairly frail but are are quite agile and can dodge most attacks resulting in them being rather decent at physical combat. All this combined together states that they can be potent if they train themselves or are trained but their natural skill is decent. The average Kitsune ranks above the average human of a similar age, although older Kitsune tend to rank above many other species as age tends to add to knowledge and skill. Kitsune tend to last for a while and simply get stronger with age, although they start rather fragile at first.