First things first, High Rise and Mainliner could easily have been the same group. High Rise was Asahito Nanjo on bass and vocals and Munehiro Narita on guitar, joined by a succession of drummers (including Yuro Ujiie, Pill and free-jazz veteran Shoji Hano in the past, and Koji Shimura currently), while Mailiner was Asahito Nanjo (bass, vocal), Makoto Kawabata (guitar) and Tatsuya Yoshida (drums). Mainliner was kind of High Rise crossed with Acid Mothers Temple.
For High Rise my recommendations are Disallow or Live, both on Squealer (
http://www.squealermusic.com/catalog/hrise.html). I'm not a fan of Dispersion or High Rise 2 as I think they're a bit underproduced and tend to wimp out a bit when they should be shredding your speakers.
For Mainliner I'd recommend Imaginative Plain or Psychedelic Polyhedron. Imaginative Plain is quite similar to High Rise, while Psychedelic Polyhedron is more like Acid Mothers.
On the subject of High Rise and associated bands, can anyone give me any recommendations regarding Munehiro Narita's solo stuff or Kyoaku No Intention?