This game is already very popular in Japan. Coming from a long line of game series :
Hiiro no Kakera (1)
Hiiro no Kakera (Fan) Ano Sora no Shita de
Hiiro no Kakera (2) Hisui no Shizuku
Hiiro no Kakera (3) Aoi Kuro no Kusabi
The story revolves around TAMAKI, who is apparently a descendant from the goddess they call TAMAYORI-HIME, the guardian of the Rifuu village~ ^^ Tamaki came to the village to stay with her grandmother while her parents worked overseas. She then learned that she was the present-day Tamayori-hime, and 5 male guardians from the five houses (or elements) had been waiting for her arrival. Along with these guardians (Takuma, Mahiro, Yuichi, Suguru, Shinji, and later on, another guardian named Ryo) plus her grandmother and friends, Tamaki managed to guard the seal which Tamayori-hime hold a long time ago for the Onikirimaru (Onikirimaru, translated as Demon Cutter, is a sword that only - much later - can be used by Takuma).
For the 2nd and 3rd seasons, there are added characters... main and side characters... ^^ while the six guardians and Tamaki are still there... For the FAN side, it's an encore to the 1st season. Much like Kiniro no Corda 2-encore! ^^