If the question were, "I bought a guitar, how do I play it?" there would be a lot of questions back about what kind of music you want to play, etc. Your specific question is a little more narrow than that, but there is a tremendous amount more to know than just how to keep it alive.
In japan there will be someone close who has kept trees alive a long time, and probably more than one. The exact answer to your question is hard without knowing how cold it is going to get, how much it will rain, etc. Find them. They know local climate.
In the meantime, if it is not raining, sprinkle water every now and then on the soil until water pours out of the drain holes, then let it go for several days until it starts to dry out. Don't try to water if it's freezing. Keep them out of hard winds. Watch for bugs. Don't fertilize until local experts say they fertilize pines. Look up species guides on the internet aand see what they say about the particular species. They will like sunlight, even in winter. They will not like being inside.
