I had a Female Mimiyortchi that evolved into the oldie Lady aka Otokitchi aka Miss Matchamker, and I had a Male Gozarutchi that evolved into a Ojitchi, and I had Oyajitchi.
*Topic moved to 'Help for New Tamagotchi Pet Owners'*
All of the Tamagotchi Connection series (V1 - V4) can turn into Old characters. If they are boys they can turn into Ojitchi and girls can turn into Otokitchi.
They do this if they don't have a baby with a partner when they are regular adults.
It is more common for them to turn into Old Characters on the V4, because the Matchmaker doesn't stay on screen very long (only 10 seconds) when she visits, so it is very easy to miss her
I have had one of my V4 adults turn into an Old Character because I missed the Matchmaker (and because I kept getting mail at the time the Matchmaker would normally visit - 10.30am / 3pm / 7pm).
As soon as he was an old man, I just kept him on pause and used my V3 to get a girl and let her evolve into an old lady, then mated them