長い時を共にした相方が眠りにつくとき、運転手は桜の苗を植える。
桜の花が咲く頃に、何度でも思い出せるように。

When a partner with whom he has spent a long time together falls asleep, the driver plants a cherry tree sapling.
So that he can remember those times again and again when the cherry blossoms bloom.