Whatever's printed on their CD is the official name, which in this case is 天上智喜 The Grace. It's just like how TVXQ's official name is 東方神起 but they're referred to as 동방신기 in Korea since it'd be a hassle for Koreans to type out the official Chinese characters all the time.
I can't wait for their Japanese debut album! <3333 I miss my girls even though they promoted Han Ban Deo, OK?! like crazy this summer... I WANT MORE NEW SONGS, DAMNIT! Especially in Japanese since their Japanese songs are so bomb. <3