The Ruler, the climactic theme used when Saitama breaks Boros' Power Limiter armor and his true potential is unleashed, giving rise to the first challenging match Saitama has during the series.Dark Energy, the theme of the overall invasion force and the battle theme of Boros, the series' first threat not just to Earth but to Saitama as well.Wet My Scales, the ominous theme of the first truly threatening villain in the series, the Deep Sea King.Rapid Speed, the theme for Suiryu's battles, is fittingly energetic and powerful.It starts out badass and menacing, but evolves into a chill and somewhat goofy guitar around the middle, perfectly representing his character. The aptly-titled Fake Star is King's theme.Bang's theme in Season 2, titled simply Martial Arts, truly evokes the image of a seasoned master.
It got a remix for season two, which is basically the same song but with more electric guitar than ever.