The official Dragon Ball website’s thirteenth entry in “The Nearly Complete Works of Akira Toriyama” — an on-going series highlighting rare and important pieces of the author’s work over the years — is the Dragon Ball chapter 187 title page from the 1988 #37 issue of Weekly Shōnen Jump (released 09 August 1988); this is incorrectly identified on the official website’s entry as being for chapter 87. The official website’s rationale for sharing the image today is that January 31 is “Aisai no Hi” (“Beloved Wife Day”), with 1 looking like the letter “I” (ai) and the number set 3-1 roughly sounding like sa-i in Japanese.
The image is mislabeled in its original serialization as being for chapter 137; this was corrected for the tankōbon release (and subsequent reprintings, including the 2016 Digest Edition version). Chapter 187 originally included its title page and two additional pages in full color, with the rest of the chapter presented in a limited color palette.
If I left Goku with the same proportions as when he was a child, there would always be things difficult to show in depicting the fights, so I started wanting to make him grow by a lot. It was at a time when Dragon Ball‘s popularity had only just started to stabilize, and manga where the main character’s appearance changed drastically were rare, so people like my editor were quite opposed to it. But, thanks to his getting taller, I came to be able to draw illustrations such as him sitting astride a motorbike.