PC-9800シリーズ
There are lots of graphic editor on PC-98. Dithering support is the top priority in those program to deal with the limitation of the system. They have features like color mask, that don't even exist modern pixel art editor.
What, Why, When of 16 color CG
English documentation on MAG format
A lot of 16 color CG and a timeline of graphic editor.
Challenging the limitation of 16 color. The author also posted a tutorial, but most images in the tutorial are lost.
with production process
The author also talk a bit on Twitter.
16 color CG in modern environment, probably using D-Pixed, as mentioned in this post.
File sharing page of a PC-98 fan site, has a category for MAG, PIC and MASL data.
This person is developing a PC-98 style game, often share screenshots and drawing timelapses to Twitter.
A detail tutorial from draft to finishing. The server is unstable, visit archived version if needed.
Interview with Na-Gaさん
The author confirmed that the character CG in Star Platinum is dotted by hand with EXルーペ.
なかむらたけし先生 looking back on painting with Multi-Paint System.
Manga about drawing graphic for PC-9801 game in the 90's.
鮪ペイント
鮪ペイント and it's plugins located inside PC98UTIL\CG&GAME\GRAPHICS\EDIT\MPS.
Demo video of Multi-Paint System (MPS), the commercial version of 鮪ペイント.
Multi-Paint System drawing process Time Lapse on niconico.
EXルーペ is a 鮪ペイント plugin for detailing and finishing. But it is so feature complete that can be used as a standalone editor.
EXルーペ and MGrad's author homepage. Download available.
The Japanese freesoft distribution site since 1995.
Online PIC/Pi/MAG/MAKI image loader
Susie is a image viewer, with plugins it could support many rare Japanese image format.
Alternative to Susie, provide easy to use file viewer with previews. Make sure to download the Grapholic GAME CG Plugin Library from here.
All-in-one game image viewer for PC-9801/9821 MS-DOS.
Open source retro image format viewer
Most 16 color CG on web are GIF/PNG. To convert them back to MAG, convert them to BMP, then use MG to convert them to MAG.
On a mordern machine with Imagegick installed:
convert EXAMPLE.PNG -alpha off -compress none \ -colors 16 BMP3:EXAMPLE.BMP
Then, in PC-98 DOS:
MG .BMP.MAG EXAMPLE -XC
GIF2BMP EXAMPLE.GIF MG .BMP.MAG EXAMPLE -XC
GIF2BMP and MG can be found in the Freeware Megapack in the "PC98 Editor/Tool" section above. They are located inside PC98UTIL\CG&GAME\GRAPHICS\CONV, named GIF2B020.LZH and MG098.LZH respectively).