Tohoshinki were the cover for monthly “FLYING POSTMAN PRESS” (already available at selected stores on 171219, though release is on 171220). The digital version will be available on the website (here) starting from 171225.
Below is a translation of an excerpt from their interview:
On why they chose to singing Begin at this timing:
YH: I have some special memory about the original “Begin” and there are many good phrases (in lyrics) such as “You and I, Begin” and “Just the two of us, Begin” and these phrases are just about the way we are right now, so I chose this song.
TVXQ! Express 