Sources used, sorry they're not really organized at all, if you have any questions just as me in the comment section

https://segafish.museebolo.ch/en/
https://archive.org/details/seamail
https://en.sega-dreamcast-info-games-preservation.com/post/a-watch-swatch-connected-to-a-dreamcast-a-canceled-accessory-of-plus
https://www.thedreamcastjunkyard.co.uk/2015/02/the-rarest-dreamcast-hardware-on-earth.html
https://www.thedreamcastjunkyard.co.uk/2015/11/nikkei-dreams-business-on-dreamcast.html
https://www.thedreamcastjunkyard.co.uk/2016/01/csk-holdings-brief-history-connection.html
https://segaretro.org/Dreamcast_consoles_in_Japan
https://consolevariations.com/database/sega/sega-dreamcast
https://www.juppongatana.cl/producto/consola-sega-dreamcast-edicion-limitada-csk-kempo/
https://twitter.com/nvmusa/status/1100200981202112512
https://en.sega-dreamcast-info-games-preservation.com/post/airbrush-dreamcasts-limited-2
https://www.wsj.com/articles/SB938514646398747859
https://www.irishtimes.com/business/sega-deal-will-let-users-of-game-consoles-trade-stocks-online-1.233716
https://www.thedreamcastjunkyard.co.uk/2016/01/csk-holdings-brief-history-connection.html
https://www.youtube.com/watch?v=Q4mFN67JOFg
https://www.youtube.com/watch?v=TyyU9oct-oY
https://www.youtube.com/watch?v=rtMwdw65ghs
https://www.youtube.com/watch?v=JEmi2PaLaO0
https://www.youtube.com/watch?v=WwZg9YgYXpU
https://www.youtube.com/watch?v=C7PF0ElO6fY
https://www.youtube.com/watch?v=8IsunECqJDs
https://www.youtube.com/watch?v=bkOsNYAx90I
https://www.youtube.com/watch?v=ObqCWmZoCqI
https://www.youtube.com/watch?v=MdW-pDcZDXA
https://www.youtube.com/watch?v=3_TSh33EQsU
https://www.youtube.com/watch?v=-7sdFyUDzlQ
https://www.youtube.com/watch?v=TvrhvQeOLmo
https://www.youtube.com/watch?v=Z2aAsw7iNOU
https://www.youtube.com/watch?v=U874NdD0ows
https://www.youtube.com/watch?v=X3oMwg8sSqw
divers vids:
https://www.youtube.com/watch?v=eHt9v8UzX_Y
https://www.youtube.com/watch?v=9eBElBVqqUs
https://www.youtube.com/watch?v=_kE7smFspnI
https://www.youtube.com/watch?v=-tgarFP3L5c