Very rare Tokyo Kogaku 東京光學 Topcor S 50 2 LTM 。. Both optics and cosmetic in almost mint condition ! The most famous for Tokyo Kogaku is Similar 5 1.5 . And second best is this Topcor 50 2 . An undervalued Len company actually for military use during WWII . Len only w filter.

https://zhuanlan.zhihu.com/p/1904088547033580715

https://leicaphilia.com/the-leica-thread-mount-topcor-50-f-2/