Japan Post announced Tuesday that it will extend the delivery time frame for Yu-Pack parcels and express mail — including Letter Pack envelopes — in certain regions starting April 1, with potential delays ranging from half a day to a full day, to cope with stricter regulations on truck drivers’ working hours.

For example, a Yu-Pack sent from a post office in Tokyo to Yamaguchi Prefecture would typically arrive the afternoon of the following day. However, beginning in April, it will arrive in the morning of the day after next.

Japan Post attributed the changes to long-distance routes that are currently handled by a single driver switching to a relay-type system using multiple drivers.