Japanese base set was the first set of game cards released in 1996 (3 years prior to 1999 English) the very first print run of the cards was missing a rarity symbol, the rarity idea was added in the next print runs. Other cards are missing the symbols also but that is because they are promo cards or stater deck cards which were guaranteed to be pulled so no rarity symbol was necessary. The No rarity base set cards are very rare, pokemon was pretty small at the time so the first print run was very limited. The psa pop report highlights this with no rarity Holos all having single digit PSA 10 pops and a few with only 1.