Sakugen (策元 1675-1699) was an heir to the Honinbo house after Honinbo Dosaku. He acquired the right after the death of the previous heir, Doteki, in 1690. However, Sakugen passed away in 1699 before becoming head of the house. Honinbo Dochi took his place after this untimely passing -- succeeding the house after Honinbo Dosaku's death in 1702.
Judging by Sakugen's records from the Castle Games he reached 7-dan status in 1693. He won all of his Castle Games, except one.
- 1693 Yasui Chitetsu - Honinbo Sakugen, B+13
- 1693 Yasui Senkaku - Honinbo Sakugen, B+3
- 1695 Honinbo Sakugen - Yasui Senkaku, B+2
- 1695 Yasui Senkaku - Honinbo Sakugen, B+1
- 1696 Dosetsu Inseki - Honinbo Sakugen, B+5
- 1698 Honinbo Sakugen - Yasui Senkaku, W+11 (final position on record given shows W+12)
- 1698 Yasui Chitetsu -Honinbo Sakugen, B+8
You can see his games here: http://web2go.board19.com/gopro/psnx_list.php?id=630. Unfortunately there are only 8-games (7-castle games and a short fuseki game with Dosaku).