Furyu released today three new 12 Sai: Koisuru Diary 3DS themes in the Japan PSN. Each of them comes with the design of the original 3DS game which released in 2016 Summer in Japan and you can buy them one by one for 200 Yen (with tax) or in one package all the three for 500 Yen (with tax).
Furyu released three introduce videos for each themes what you can watch in here:

It should be noted that on Februray 1, 2017 released three more 12 Sai: Koisuru Diary themes for 3DS with the same conditions (prices). You can already watch in here the videos and you can find the pictures in the gallery: