Yes, you can exchange on weekends and holidays.
USD：BUY ¥143.28/SELL ¥139.00
EUR：BUY ¥158.58/SELL ¥153.75
GBP：BUY ¥189.83/SELL ¥174.78
CNY：BUY ¥20.98/SELL ¥18.15
HKD：BUY ¥19.22/SELL ¥16.86
KRW：BUY ¥0.1176/SELL ¥0.0926
PHP：BUY ¥2.79/SELL ¥2.19
SGD：BUY ¥111.81/SELL ¥104.14
THB：BUY ¥4.71/SELL ¥3.84
CAD：BUY ¥106.68/SELL ¥97.75
AUD：BUY ¥99.17/SELL ¥86.84
NZD：BUY ¥91.99/SELL ¥81.14
TWD：BUY ¥4.83/SELL ¥3.96
CHF：BUY ¥169.18/SELL ¥161.34
MYR：BUY ¥36.74/SELL ¥28.98
VND：BUY ¥0.01/SELL ¥0.005