Ikuchi is an HTML/Javascript application which uses Three.JS to render 3D views of solar system magnetospheres. It is designed for quickly viewing the realistic 3D and time-dependent geometry of giant planet magnetospheres, particularly Uranus and Neptune. The scenes are viewed in a coordinate system with one axis pointing from the planet towards the Sun, and another pointing from the planet in the direction of its orbital motion. You may know this as a "Planetary Solar Orbital" coordinate system, e.g., Geocentric Solar Ecliptic (GSE) at Earth, or Kronocentric Solar Orbital (KSO) at Saturn. The orientation of the planets as a function of time is computed from non-linear functions fitted to data from NASA/JPL Navigation and Ancillary Information Facility (NAIF)'s SPICE system. The RMS errors associated with fitting to SPICE data are no larger than 0.06 deg, and most planets have a maximum errors no larger than around 0.03 degrees, apart from Jupiter and Saturn, which have maximum errors of around 0.2 degrees. Although the fits are generally very accurate, Ikuchi is not designed for accurate ephemeris. The orbits of natural satellites are especially simplified.