The last maintenance attention we give the Pine in our garden (Pinus leucodermis, Abies procera, Pinus mugo, Pinus densiflora, etc.) in October/November is called momiage.
This year the coloration, from green to brown, happened in just one or two weeks time, the first weeks in October.
Momiage is about removal of old and dead needles and can be combined with thinning back to one or two new shoots with a second midoritsumi, that is removal of (part of) the second flush of bud growth, if required.
If you want the tree to look denser during winter then you can decide to postpone this activity until the next spring.
Be aware to cover your wrists and arms to protect against the needles during these activities. Cloves are also an option. In Japan one often uses special sleeves.