Turns out they used to be one conglomerate, but World War II changed that [0]:
> The Mitsubishi Group traces its origins to the Mitsubishi zaibatsu, a unified company that existed from 1870 to 1946. The company, along with other major zaibatsu, was disbanded during the occupation of Japan following World War II by the order of the Allies. Despite the dissolution, the former constituent companies continue to share the Mitsubishi brand and trademark.
I used to think it's cool the same company makes a pencil and an F-16 derivative ( https://en.wikipedia.org/wiki/Mitsubishi_F-2 ), but alas, the pencilmaker is not the same company.
I'm tempted to write an small blogpost about this one with some explanations, as that blogpost is a bit old :D but there's a couple things I found in this rabbit hole I fell:
First, as some of you have noted, the 三 kanji means 'three' [0] and Mitsubishi means 'three diamonds' [1]. Hence, the traditional family crest from the Mitsubishi family. The concrete origin can be found around here [2]
Mitsubishi Pencil is the first one registering the three diamond logo, in 1903 [3]. Mitsubishi zaibatsu logo was thinner and a bit different then [4]. During the occupation of Japan after WWII, the Allied Powers (GHQ) ordered dismantling the zaibatsu and stopping using the Mitsui and Mitsubishi brands (among others) [5]. Mitsubishi Pencil was not part of the zaibatsu, but using the same name, it was in risk of disappearing. After negotiations by their president with the GHQ they were allowed to keep it if they indicated that they're not part of the zaibatsu [6]. Back in the fifties you could see "non-zaibatsu" under their logo in their products. [7]
The 'Mitsubishi Cider' made by Konyusha doesn't exist anymore but its trademark was registered by Mazda Kogyo (now Mazda Total Solutions) in 1919. No, not THAT Mazda, a different Mazda (Matsuda/Mazda is a Japanese surname, so, more confusion :D) Mazda Kogyo would have contracted Konyusha to manufacture and sell the product in 1919 [8]. In 2014 Mazda Kogyo transfered the brand to Mitsubishi Corporation while Konyusha was still manufacturing it, and in 2015 they changed their name to Mazda Total Solutions [9]. Haven't totally understood their message, but I think Mazda Total Solutions has ceased operations as of today [10]. Konyusha stopped manufacturing and selling the cider in 2017 [11]. I've seen somewhere that could be related to the Kumamoto earthquake of 2016, as that Konyusha's location.
Fun fact, there's is a cider named "Mitsuya Cider" [12] that has a similar logo, but with "arrows" instead of diamonds. When it started, as a carbonated water brand in the 1880s, it was part of the Mitsubishi zaibatsu, but it was split from the company a couple years later [13].
> The Mitsubishi Group traces its origins to the Mitsubishi zaibatsu, a unified company that existed from 1870 to 1946. The company, along with other major zaibatsu, was disbanded during the occupation of Japan following World War II by the order of the Allies. Despite the dissolution, the former constituent companies continue to share the Mitsubishi brand and trademark.
[0] https://en.wikipedia.org/wiki/Mitsubishi