Just because there is guitar and bass in the song doesn't mean a song can't be pop.
Pop music is generally described as very commercial friendly, marketable and memorable, with either vocals, lyrics, instruments, or a combination of all three creating catchy choruses or verses. Pop music is also known for its ability to attract listeners through its versatile sound since it pulls from a plethora of musical influences. It can be also fair to say that pop music is predominantly image driven, especially through the subject matter of the lyrics, live performances, music videos, and other forms of exposure which makes it favourable and unfavourable to whoever is the listener.
To me that seems pretty Gackt. Pop doesn't have to be like Britney Spears. Pop can be a sub genre to Rock, Country, R&B, anything really.