Ok look, LA knows this anime isn't for LA's demographic but LA is kinda a sucker for romance anime and LA watched the ONA for this years ago and wanted to see how this would get the full anime treatment that Houkago no Pleiades did.
12-sai follows the relationships of 12 year olds of Hanabi Ayase voiced by Ai Kakuma and Yuuto Takao voiced by Soma Saito as well as Hanabi's friend of Yui Aoi voiced by Juri Kimura and Kazuma Hiyama voiced by Shun Horie and follows their experiences and obstacles in first love and follows some typical cliches of the romance genre.
If LA could analyze the two relationships, Hanabi and Yuuto's one is the more generic one out of the two, with Yuuto pretty much solving EVERYTHING that comes into his and Hanabi's relationship with his smooth-talking to coincidental incidents, if anything LA is reminded of Usui from Kaichou Maid-sama as the main character who "can do no wrong and EASILY fixes any obstacles in his and Hanabi's relationship", Yuuto and Hanabi's relationship right from the start is TOO stable and leaves little room for growth as LA's biggest annoyance to this relationship is Yuuto solving everything by himself and for a relationship with no flaws and hardly moves up (sure their 12 years old, but still!!, we get invested into a relationship for them to grow, not do the same things over and over and over again), is a hard relationship to get invested in. Yui and Kazuma's relationship however gives us something more than that, that of a twice shy relationship but with a role reversal we usually see in a romantic genre, the role reversal in this relationship is that the male is the tsundere while Yui is the headstrong *ahem* "give no shit what you think" character of the relationship and because Yui and Kazuma goes through their own obstacles by tandem from Hanabi and Yuuto's but they however not only resolve their obstacle but they give us character development, growth and depth (most noticeably Yui as a character development angle and Kazuma in a relational development angle) and for that, Yui became LA's favourite character of this series.
Onto the other characters, Coco is your typical "rival-ojou love interest villain" girl for Hanabi and she is HIGHLY predictable in failure due to Yuuto resolving everything, Coco...you just can't win...just give up and on speaking of giving up, the three idiots are WALKING ANNOYING COMEDIC RELIEF and their running gags of "wanting to emulate Yuuto's manly quotes" to just plain out causing some of the cliche obstacles thrown at the two core relationships, the three idiots really are double edged swords, they move the plot forward predictably but are also annoying useless comedic trio. Huh...LA didn't think that Maid-sama would have more relevance in this anime review but whatever. Marin at the very least have a purpose to be a thoughtful best friend to Aoi and Hanabi and when they are in doubt, they go to her for advice, IRONIC as most of her advice although thoughtful as being the friend of the both of the core female characters, her advice is unneeded for the most part. Finally rounding up the cast, LA will point out the "other" love rival to Yuuto and Hanabi's relationship by the name of Ayumu Tsutsumi voiced by Tetsuya Kakihara, well the biggest problem with him is that his screentime is soo low he just becomes a one-off "love rival" against Yuuto...he's by the by for a love rival, very forgettable in the long run.
In terms of voice acting, there tends to be LOTS of squeak that can get really annoying (LA is looking at you Ai Kakuma and the three idiots), however once again Yui's voice actor Juri Kimura was LA's favourite voice actor, she actually tries to sound like a 12 year old and actually ACTS like on to without the squeak aside from Juri Kimura, LA actually liked Sayuri Hara who voices Cocoa as a "playing against the type" role for Sayuri as she usually voices genki-type characters...this role as Cocoa for Sayuri is a complete 180.
In terms of animation by OLM, Inc who helms this anime from SynergySP from the OVA, they're character designs have similarities to the OVA's but more "sparkly" typical considering this is a typical shoujo anime, however with it's comedic moments, the animation goes full chibi with blank circle eyes animation and LA can see that it IS a comedic moment thus can be playful but in animation sense, LA can just see this as being "kinda lazy" and not take the comedic moments in a stronger sense. Overall, animation is janky between it's shoujo-romance and comedy moments.
With all these faults and promising elements to 12-sai has, overall, LA can easily say that IT IS a cliche storm of romance tropes just heavily toned down due to the demographic they are trying to show this anime too and to be completely honest as cliche as it is, it's still hits the mark at pleasing it's demographic, it's cutezy puppy love with no high-tension drama, but still having the typical romance anime tropes we see, it even makes sense from it's animation quality standpoint as it's chibi and comedic for the most part shows us the tone of the anime throughout.
12-sai is getting a 2nd season so if the 2nd season can do something MORE especially with Yuuto and Ayase's relationship instead of being the ever-stable relationship that never changes, then LA will honestly say that the 2nd season will be pointless. 2nd season hopes aside, 12-sai's first season at best is an "ok" romance shoujo anime in the cliched view of a 12 year old and that's not such a bad thing.
