>>2452886That happens to me when there are two meshes that are not connected but are overlapping and are on the same object, like hair for example, many hair locks are overlapping but are not part of the same mesh, I just separate them into different objects and then export, this problem is visible on PMXe and MMD, if the problem is only visible on MMD then disable double sided materials if possible, the lines problem in MMD is due to it's anti aliasing, solved through Nvidia inspector, if you can see it on PMXe then it is due to a problem with the exporter, some people import the model with those lines into Metasequoia the re-export it and that gets rid of the lines, haven't tested that myself though.
