Here's the L5R TTS online deck builder
http://infamous-irc.com/dengeki/l5r-deck-generator/
They have an example list for reference:
# Lines starting with # are comments # Lines starting with - are the start of a named face-down pile of cards # Lines starting with + are the start of a named face-up pile of cards # Lines starting with a number are cards # Card names are case insensitive and may be partially matched # This example is the offical suggested Lion Clan starter deck + Provinces 1 Manicured Garden 1 Ancestral Lands 1 Night Raid 1 The Art of War 1 Shameful Display 1 Yojin no Shiro 1 Keeper of Water - Dynasty # Neutral 3 Otomo Courtier 3 Seppun Guardsman 2 Keeper Initiate 3 Miya Mystic 3 Wandering Ronin 1 Favorable Ground 1 Imperial Storehouse # Lion 1 Obstinate Recruit 1 Ikoma Prodigy 1 Matsu Berserker 1 Steadfast Samurai 1 Akodo Gunso 1 Deathseeker 1 Venerable Historian 1 Kitsu Spiritcaller 1 Pride Brawler 1 Matsu Beiona 1 Honored General 1 Ikoma Eiji 1 Akodo Toturi 1 Staging Ground - Conflict # Neutral 2 Fine Katana 2 Ornate Fan 2 Banzai 2 Court Games 2 Charge! 2 Fallen in Battle 2 Rout # Unicorn (9/13 influence points) 1 Iuchi Wayfinder 1 Ide Messenger 1 Favored Mount 1 Spyglass 1 Breakthrough 1 Captive Audience # Lion 1 Vengeful Oathkeeper 1 Master of the Spear 1 Guidance of the Ancestors 1 Honored Blade 1 Sashimono 1 Ready for Battle 1 Stand Your Ground 1 Way of the Lion 1 For Greater Glory 1 Strength in Numbers
The good news is that you can copy/paste the vast majority of your decklist from fiveringsdb.com into the deck builder and it will function properly. Just, after you copy the cards (Simple highlight on fiveringsdb, copy, paste into deck generator), add the headers "-dynasty" and "-conflict" above the respective piles. Then copy the provinces, role and stronghold from fiveringsdb, remove the element call outs (copy/paste from fiverings will say "Water Rally to the Cause." Delete the word water.) Then add a 1 in front of each of your provinces, role and stronghold and put it under the header "-provinces"
You don't need to delete headers like Characters (34) or anything from the fiveringsdb copy/paste, as the deck generator simply ignores things that don't have a number, #, - or + in front of them. In fact, it even ignores # because that just indicates notes for your reference and isn't included in the deck list prepared.
It's not as seamless as Thronesdb into OCTGN, but it's not laborious or time consuming.