  We investigated the formation of arc-like structures in the infalling
envelope around protostars, motivated by the recent Atacama Large
Millimeter/Submillimeter Array (ALMA) observations of the high-density
molecular cloud core, MC27/L1521F. We performed self-gravitational
hydrodynamical numerical simulations with an adaptive mesh refinement code. A
filamentary cloud with a 0.1~pc width fragments into cloud cores because of
perturbations due to weak turbulence. The cloud core undergoes gravitational
collapse to form multiple protostars, and gravitational torque from the
orbiting protostars produces arc structures extending up to a 1000~AU scale. As
well as on a spatial extent, the velocity ranges of the arc structures,
$\sim0.5\,\mathrm{km\,s}^{-1}$, are in agreement with the ALMA observations. We
also found that circumstellar disks are often misaligned in triple system. The
misalignment is caused by the tidal interaction between the protostars when
they undergo close encounters because of a highly eccentric orbit of the tight
binary pair.
