You might consider:
Dale Furutani's Matsuyama Kaze series:
1. Death at the Crossroads
2. The Jade Palace Vendetta
3. Kill the Shogun
I.J. Parker's Sugawara Akitada series:
1. Rashomon Gate
2. The Hell Screen
3. The Dragon Scroll
4. Black Arrow
5. Island of Exiles
6. The Convict's Sword
7. The Fires of the Gods
8. The Masuda Affair
9. Death on an Autumn River
10. The Emperor's Woman
11. Death of a Doll Maker
12. The Crane Pavilion
Eiji Yoshikawa' s novels:
Musashi
The Heike Story
Taiko
Laura Joh Rowland's Sano Ichiro series:
1. Shinju
2. Bundori
3. The Way of the Traitor
4. The Concubine's Tattoo
5. The Samurai's Wife
6. Black Lotus
7. The Pillow Book of Lady Wisteria
8. The Dragon King's Palace
9. The Perfumed Sleeve
10. The Assassin's Touch
11. The Red Chrysanthemum
12. The Snow Empress
13. The Fire Kimono
14. The Cloud Pavilion
15. The Ronin's Mistress
16. The Incense Game
17. The Shogun's Daughter
Takashi Matsuoka's novels:
Cloud of Sparrows
Autumn Bridge
As well, the Historical Novels site (
http://www.historicalnovels.info/Asia.html#Japan) should provide you with other options.