This was a private live concert arranged for industry insiders and media on 1998.06.12 at Aoyama Spiral Hall. This is strictly speaking his first live after the hiatus. Sing a Song (album) was released on 1998.06.24 while Heart (single) was released 2 months earlier 1998.04.30. The entire concert was subsequently shown on TV.
Only 2 songs from this acoustic concert were officially released in the Fukuyamania VTR in 1999 (DVD 2001). So the rest you see are basically VTR quality TV-rips of 12 years ago.
Comeback concert in June 1998 after 3 year hiatus, closed to the public but broadcast on TV later on in conjunction with release of the album Sing A Song