I'd like to share a small tool by TTEMMA (with author's permission), if someone is interested.
There are 2 tools, actually.
Zar.exe can extract/repack .zar containers from Zelda: Ocarina of Time 3D.
Gar.exe can extract/repack .gar containers from Zelda: Majora's Mask 3D (but not .gar.lzs files...