Janus particles exhibit interesting self-assembly behavior and functional performances. In particular, soft and deformable Janus particles, as diverse as Janus micelles, Janus microgels, and Janus dendrimers, should receive more attention due to their unique chemical and physical properties and enormous potential applications. Gaining control over precise and predictable self-assembled structures and understanding the fundamental details of self-assembly remain a formidable challenge. Here we present a novel mesoscale model for soft Janus particles, which successfully reflects their physical nature by directly mapping onto experimentally measurable particle properties. By properly tuning Janus balance and the strength of attraction between attractive patches, soft Janus particles can reversibly self-assemble into a number of fascinating hierarchical superstructures in dilute solutions, such as micelles, wormlike strings, single helices, double helices, bilayers, tetragonal bilayers, and complex supermicelles. Our work demonstrates that soft Janus particles with deformable and non-centrosymmetric characteristics hide many surprises in the design and fabrication of hierarchically self-assembled superstructures.