I just watched the last episode of Petopeto-san, and while it wasn't exactly the ending I expected, it was definitely a fun series to watch overall. Looking back on it, this series was a lot like Snow Fairy Sugar--at first glance, you might dismiss it as just cute, but it also dealt with more serious topics underneath.
The main characters in Petopeto-san are Shingo, who's your average human guy with a gift for making really good ramen, and Petoko, who's a youkai (monster), or as the politically correct term goes, a "specified race". The underlying plot to the series is how the youkai and normal humans get along, with some in their school disliking the youkai and being racist towards them at first, but eventually coming around to see deep down they're the same as everyone else. Since the governor of Tokyo routinely makes racist statements and seems to get re-elected anyway, I was pleasantly surprised to see an anime series promoting tolerance and understanding the way Petopeto-san does (although I know Ishihara doesn't speak for everyone in Japan's view of foreigners, so I shouldn't have been surprised).
Shingo first meets Petoko when she falls into the pool one day at school, he reaches out and grabs her hand, and she promptly gets stuck to him. Petoko is part of a race of youkai that has the ability to stick to people, supposedly so they could seduce them. She's stuck to Shingo until they both fall asleep, which is going to take a while since this happened in mid-afternoon. Talking back at his house, Petoko explains she was unable to go to school until now because she stuck to people, even though she always wanted to go. She's afraid her brief school life is over, but Shingo convinces her it's OK and helps cheer her up. From there, Petoko becomes popular in school, her sincerity and earnestness winning people over. No school life series is complete without a love triangle, and Kuguru, who's a kappa youkai and a little rough around the edges, fills that role, since she has a crush on Shingo, and Shingo likes Petoko.
I thought the Shingo-Petoko-Kuguru triangle was handled really well--Shingo doesn't vacillate back and forth on who he likes, Petoko's feelings are developed slowly and realistically, and the way Kuguru shows she likes Shingo (which could easily be mistaken for picking on him) is believable too. The last episode is well done, resolving who likes who (not that it was in much doubt), and taking a more serious turn but avoiding getting melodramatic. I would've liked to see a little more closure at the end (first Lamune, now Petopeto-san--it's like no couples kiss at the end of anime series anymore...), but everyone involved is young enough that there's plenty of time for that later.
The animation and voice acting was pretty good throughout--Petoko's Osaka-ben accent felt a little out of place somehow at first, but I got used to it quickly. The stretch towards the end of the series with the "little sisters festival" was a little odd and seemed to sidetrack the story somewhat, but the ending pulled the story back to its original track. Petopeto-san was a short, but sweet series--I can definitely see it having re-watch potential.