The refractive index of hydrophobic silica aerogel has reached up to 1.26 by inventing a newproduction technique, pinhole drying method, which can control the bulk density of synthesized alcogel. Itwas shown by optical measurements that a transmission length of 60 mm at 400 nm wavelength was achieved at a refractive index of 1.06. Clear Cherenkov ring images and sufficient photons can be obtained from aerogel tiles with ultra-high refractive indices of 1.10-1.23 by a charged beams experiment. A prototype proximity focusing ring imaging Cherenkov counter, in which new transparent aerogel tiles were installed as radiators, for the Belle-II experiment marked sufficient photoelectron yield, achieving over 5σ π/K separation capability at a momentum of 4 GeV/c.