We develop a novel mesoscale simulation model in order to study the hierarchical self-assembly of soft disklike particles in dilute solutions. In suitable solvent conditions, the soft anisotropic disklike particles first self-assemble into one-dimensional flexible threads, in accord with experiments. Then, intriguingly, the threads reversibly pack into flexible hexagonal bundles by decreasing the solvent quality. Hierarchical self-assembly of this type may be important to provide a strategy to create bundle structures by bottom-up self-assembly with a single type of soft and flexible building block and mimic the bundles commonly found in biological structures.