Is that not a normal thing for mangas? Light novels have character sheets every volume, often barely changed, all the time. This one has some whimsy, at least.
If you by manga volumes and have a break between them, it helps to have character bios to relearn the cast. I think it's more common among slice of life series with big casts. For example, Chichi to Hige-Gorilla to Watashi has this for each volume.
Even after the world is swallowed by the sun and is not but ash, Yoshio will remain! Hail Yoshio, hail to the immortal King of the Ashes and the future King of the Void after the end of time! HAIL YOSHIO!