I once saw on Youtube some videos by a Japanese band, in which they performed their songs. I remember the videos and what one of the songs sounded like, but I can't remember the artist's or band's name, or the titles of any of the songs.

My memory of it may not be the best, but I will describe how I remember it.

In the videos, they performed in a recording studio. As for the design of the studio, it was not too far removed from what you might see in a café, with dominance by brown colors, plenty of wood decoration, and the stage lights around giving warm lighting.

I remember all the members being male. Don't quote me on this in particular, but the lead singer may have been shown wearing a hood, a green shirt and khaki pants, and some facial hair, probably a mustache.

As for the song, it starts off calmly. Here's a rough transliteration of one of the lyrics during this point.
"Daiji naia kua atemo, no, no no. Sei (or "say") no, no, no."

Then the song becomes faster and more energetic, introducing new instruments in the process. During the faster part, one of the lyrics is the English phrase "I love you."