Masazumi was born in 1565; he was the eldest son of Honda Masanobu.
Ieyasu trusted Honda sufficiently to have relied on him as an intermediary for diplomatic initiatives with China.
[1] Later, Masazumi served at the siege of Osaka; in 1616, he became a toshiyori; this was the position that would soon after be renamed as rōjū.
In this role, he worked closely with the now-retired second shōgun, Hidetada.
However, in 1622 he fought with Kamehime (Ieyasu's first daughter), fell into disfavor with Hidetada, and was exiled to Yokote, in the Kubota Domain.