I'm intrigued by that blue object. May I ask how you imported that in the game? Is it possible to overlay that object somehow in the creator and tweak the character to match it? Would it be possible to import something like that for ZZZ characters? I would love to try and tweak on some of them but I don't even know how to begin.
So the process is quite easy.
There's this page with models that can be used with MMD plugins:
Download Now!
gf2exilium.sunborngame.com
You can also find the models on this website, but it requires an account:
模之屋(PlayBox)是一个专业模型创作分享社区，海量模型作品一手掌握，找模型就上模之屋! 专注多品类3D模型下载、原创作品分享、软件学习
www.aplaybox.com
So you download some model, then make sure that you have a MMD plugin installed into your Blender, then just simply import it into Blender.
When you get it into the Blender you just need to remove all the not needed parts of the models, so clothes etc.
You don't need to mark everything manually in the edit mode, you can just press the L button which selects entire segments, then delete button and delete vertices, edges or faces. The alternative is pressing the N button which will show plugins on the right side, then select the one for MMD. Select the model by pressing it, then under "Model Setup" there's "Mesh" with "Sep by Mat (High Risk)" option, it will separate the model into many parts that can be deleted, but usually it's still better to do it "manually", of course you can mix these methods since in some cases it will really save a lot of time.
Keep in mind that your model that you want to get into Studio can't have more than 60k triangles.
If you by any chance get the error message in the Studio (that you exceeded the triangles limit) then just simply press Alt+Z in Blender while in Edit Mode, then just simply split the entire model into parts from the top to bottom (you can use the P button to separate mesh), then export them as separate OBJ files.
After that you just export the model as .obj file and get it into your Studio and use that as a reference.
By default if you press the O button it will show a window for importing objects into Studio, then select your ".obj" model and just import it.
I don't know if it's possible to get a model like that into the Char Maker, but then there's still the issue with adjusting the pose since the T-pose in Koikatsu is a little bit different compared to what you get in Girls Frontline 2 and I had to enable "IK" stuff and adjust some nodes.
I also recommend to switch the material to "Goo".
To get the basic body properties right I would recommend to at first check the height of the model in Blender (in centimeters), then adjust it in Koikatsu to match that height. Then in Blender you take a screenshot from the front and side (by pressing Num1 and Num3, then taking a screenshot) and use that as a reference (so copy images to "Koikatsu\UserData\bg" folder and load them in the Chara Maker). When you are done with the basic stuff You can start to adjust it more by using the imported 3d model in Studio as a reference.
So basically you have both Studio and Chara Maker open at the same time and just switch between them, you can also use the Bonemod Editor in Studio and then copy settings to the Maker when you are done, but it's always recommended to use the default sliders first, then these from the Bonemod Editor if you can't adjust them normally.
I also don't recommend adjusting the arms and legs in only one axis, it will cause some stretching when switching between poses, generally it can happen to any body part, so you need to adjust bones in a smart way.
thigh00 and
arm00 and
cf_j_shoulder or
cf_d_shoulder - if you want to adjust them then do it in every axis at the same time (so let's say 0.95 value for X, Y, Z).
I noticed that lots of people (including people who make paid cards) just adjust these in only axis (Y axis in case of thigh00, then increase cj_j_leg01 value also in only one axis) to let's say make the legs shorter, or the upper part, but it just causes some weird stretching.
Playing around with bonemod stuff also might affect how the outfits look like, so that's another thing to consider when you start to adjust them.
If you try really hard then I bet it's possible to create an almost 1:1 copy of models from other games in KK, but that requires some effort and knowledge about editing the bones, so the knowledge about which could cause stretching when you switch the pose, for example you can edit "spine" bones in X axis only and it won't cause any major issues, the other ones require editing all X/Y/Z at the same time.
This adjusted Suomi card isn't perfect either, it would still need a little bit of work to get it 100% right (right now I would say it's like ~95% right).
There's also a trick with an easy modifying the head related accessories as long as they are binded to the "Center of head" parent, you just simply use the
a_n_headside bone to switch the scale or move it in all outfits at the same time.
www.pixiv.net 
