Dengeki PlayStation D7 (Vol.73 special issue) with CD-ROM: lain TV commercial
Feature noting that a TV commercial for the game had been airing since March 1998 and that the commercial was included on the bundled disc; the article refers back to the magazine's earlier exclusive reveal (OCR reads Vol.59, probably Vol.69). Listed as a June 1998 release at the time.
Sources: archive.org