Brand: Mitsubishi Pencil Co.
Made in: Japan
8B is quite rare. Mitsubishi has not ever announced its existence. On its reverse side, three letters are printed, called "Kou-Hitsu Yo"."Kouhitsu" means pencil, pen, ball-point pen etc. in contrast with writing brush (Mo-Hitsu). In addition, it also means to transcribe ideal examples of letters or short sentences with Kouhitsu in order (especially for school children) to master how to write practically beautiful letters. Pencils softer than 4B is preferable for "Kouhitsu."
UPDATE: Mitsubishi officially expanded the lead for the Hi UNI, however the 8B is not marked in the set as it is marked on the reverse here.
Founded in 1887 and formerly known as Masaki Yomato, Mitsubishi Pencil Co., Ltd. is best-known today for its uni-ball brand of quality writing instruments sold worldwide. Curiously, this Tokyo-based business is unrelated to Mitsubishi Motors and other brands within the Mitsubishi Group. Same name, same logo, completely different company.