These cards are both from the 1999 BBM Lions set. This was a 51 card box set that commemorates the 20th Anniversary of Seibu buying the Lions and moving them to Tokorozawa. As a happy coincidence, the Lions had just drafted Matsuzaka the previous fall, so the set was able to feature two cards of the then highly touted rookie pitcher, a "regular" player card and one showing him with his manager Osamu Higashio (I think it's from the day they introduce the newly drafted players to the press). The rest of the set featured cards of the 1999 Lions, some highlights of the 1998 season (Lions won the PL pennant) and 13 cards featuring OB Lions players - Koji Akiyama, Koichi Tabuchi, Kazuhiro Kiyohara, etc. There was also an insert card featuring one of four possible players.
This is one of the only BBM sets that I'm aware of that does not have BBM's logo on the front of the cards.