12-sai.: Chicchana Mune no Tokimeki

The main heroine in both anime are a bit different in terms of personality and background but both stories are similar in that both girls deal with the problems that come with being a 12 year old girl including love. 

Both is about kids going through puberty and falling in love.  

Both are shoujo romance anime that are very cute and light hearted. They keep away from drama a lot of the time. Both anime have the main couple (or in Age 12's case, couples) get together very early on in the show so that the anime can focus on the relationship of the newly formed couples. Both anime deal with the feelings of being in a relationship for the first time and it's very quirky and adorable. The couples get nervous and flustered over the slightest things. The couples in both Ore Monogatari and Age 12 are madly in love with eachother but are quite naiive when it comes to being a boyfriend or girlfriend. One of the couples in Age 12 is also very similar to Yamato and Takeo. The episodes in both anime consist of simple slice of life aspects and they're both very cute, sweet and heartwarming shows! Also both are cheesy but in a good way. read more 

Both feature very innocent and light hearted female protagonists who are still in the process of finding themselves and understanding emotions and love. Both are supported by two close female friends through their process of growing up and fall for the most popular and outgoing guy in class. Only difference is their ages. 

- One word, CUTE. - Pure and innocent love at a young age - In both shows the characters blush excessively and get shy easily when it comes to eachother and feelings - Slice of life of couples lives from first dates to first time holding hands - Both are few of romance series out there where you can watch a couple start dating within the first few episodes!  

Both anime are about couple of lovers. In 12-sai there are two couples, in Tonikawa - one couple. These animes show walking, dating and communication of lovers, and also their problems. 

Mizuiro Jidai might be a older anime but it deals with middle school love and school girl problems just like this show both having a leading girl starring in them.  

Both series focus on the lives and experiences of latter-stage elementary school girls, with Mitsuboshi more of a slice of life series and 12-sai focusing on the romantic relationships of the characters. 

Both have a kind but dense 12 year old girl main protagonist with twin tails. Both shows have romance but gakuen alice is more focused on fantasy, comedy and its story goes a lot deeper than 12-sai