A couple girls have mentioned this as a term already in the Mori Girl community, so this one isn't entirely my own making.
This variations consists of little to no lace, heftier, simpler fabrics and silhouette, and looks more suitable for an actual romp in the woods. It can contains hints of any kind of variation of Mori, but the consistent thing in each is the sturdy, and useful feel.
I stole this term from Lolita, but I think it applies here as well. Over the Top Mori, or OTT, is usually like any other Mori outfit, but paired with things like antlers, large, unusual, and decorative accessories or clothing, and fawn makeup. This could also be an outfit with more than the usual amount of layers, to the point of almost being excessive.
Keep in mind OTT is not a derogatory term, but just a way to distinguish this variation. I happen to love this variation, I just probably wouldn't wear it as an everyday fashion. I've mostly seen this variation used for costumes, photo shoots, and fashion shows.
This variation is very simple. Basically, it's everyday clothes with hints of Mori, or it can also be extra simplified versions of a Mori coord.
Maggie, from Dollie Diaries, puts together lovely Casual Mori coords.
Yama means "Mountain" in Japanese, so this variation contains more things suitable, hypothetically, for a climb. Unlike Mori, this variation includes many bright colors and I've even seen a few with neon colors. Boots and backpacks are a must. And sometimes this style can look very similar to Mori, but other times it looks more like an outfit from a sporting goods store.
Yama girl is an already established term, and can be considered a variation of Mori, but could also be considered a sister style of Mori as well.
Hama means "Beach" or "Seashore" in Japanese, so this variation focuses more on nautical themes. Stripes, reds and blues, and sailor collars are common. Coords usually contain fewer layers, and are simpler, mainly because of the heat that usually accompanies the seashore.
Hama Girl is also already an established term, and can also be considered a sister style rather than a variation.
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