Calculators, methods, and non-transitory machine-readable mediums for convergence of a variety of communication sources are presented. Reflecting means 10 includes fluorescent light reflecting layer 11, phase difference layer 12, and polarizing layer 13 deposited in that order. In the transverse folding step, a portion of the preparatorily folded airbag located rearward of the gas inlet port is folded back in two toward a lower side of a lower part of the circumferential wall to bring a rear end thereof closer to the gas inlet port.