Niconico is the birthplace of MMD. Many legendary models (such as the iconic and Tda式 Miku ) originated here. While the interface is in Japanese, using browser translation makes it navigable.
As you download more models, your folder can become a chaotic mess of Japanese and English filenames. Stay organized with these tips: mmd model downloads
Several game developers release official MMD models for fans to use in non-commercial animations: Tutorial: How to find MMD model links ... - DeviantArt Niconico is the birthplace of MMD