A topic from AEG's L5R CCG Rules forum, copied for Oracle of the Void from a copy of the forum saved in October 2015, so pages it didn't save are missing. Players' names are left out; the rules officials are named. Rulings are as they stood on these dates; later rulings, the rulebooks and the Rules Archive may differ.
A player, 13 February 2012
I have Seppun Sensei in play. 1) Does it prevent me from using effects that would negate my Honor loss (such as Hantei Naseru's first reaction)? 2) If Hantei Naseru's second reaction is activated, will I be unaffected by the honor gain reduction? 3) If Darling of the Season has resolved and I suffer a single 7-point Honor loss (such as Shame), will I lose 5 or 7 honor? 4) If my opponent plays Deeds not Words, will my relevant honor gains become losses?
Seppun Sensei [...] Your Honor losses and gains cannot be changed, redirected or copied.
Darling of the Season Until the end of the game, each player cannot lose more than 5 points of Honor in total from other players' cards in a single turn.
Hantei Naseru Political Reaction: When any player loses Honor, discard the Imperial Favor to negate the loss. Political Reaction: When your turn begins, discard the Imperial Favor as a cost for this action and name a phase. Until your next turn begins, lower all Honor gains to half, rounded down, during that phase of each player's turn. [...]
Deeds, not Words Political Open: Target a player. Until the end of the turn, that player gains 1 Honor in addition to any other award when one of his Personalities wins a duel, and 1 additional Honor for each opposing card destroyed in the Resolution Segment of battle. Honor gains from any other source are counted as losses instead of gains for that player.
Jon Palmer (rules official), 13 February 2012
I have Seppun Sensei in play. 1) Does it prevent me from using effects that would negate my Honor loss (such as Hantei Naseru's first reaction)? 2) If Hantei Naseru's second reaction is activated, will I be unaffected by the honor gain reduction? 3) If Darling of the Season has resolved and I suffer a single 7-point Honor loss (such as Shame), will I lose 5 or 7 honor? 4) If my opponent plays Deeds not Words, will my relevant honor gains become losses?
Seppun Sensei [...] Your Honor losses and gains cannot be changed, redirected or copied.
Darling of the Season Until the end of the game, each player cannot lose more than 5 points of Honor in total from other players' cards in a single turn.
Hantei Naseru Political Reaction: When any player loses Honor, discard the Imperial Favor to negate the loss. Political Reaction: When your turn begins, discard the Imperial Favor as a cost for this action and name a phase. Until your next turn begins, lower all Honor gains to half, rounded down, during that phase of each player's turn. [...]
Deeds, not Words Political Open: Target a player. Until the end of the turn, that player gains 1 Honor in addition to any other award when one of his Personalities wins a duel, and 1 additional Honor for each opposing card destroyed in the Resolution Segment of battle. Honor gains from any other source are counted as losses instead of gains for that player.
Please note that any and all of these rulings may change once the Oracle of the Void is released - in particular #4, which is a ruling I remember from playing at the time but could easily be changed with the updated wordings on Seppun Sensei and Deeds, Not Words.
1. You may use abilities such as Hantei Naseru's first reaction, but the Sensei will prevent them from applying.
2. You will be unaffected by the honor gain reduction from Hantei Naseru's second reaction.
3. Darling of the Season will attempt to partially negate the honor gain, and Seppun Sensei will cause this partial negation to fail.
4. Edit: It's been pointed out to me that the Gold Edition MRP of Deeds, Not Words uses a wording that creates a substitution effect, which Seppun Sensei will stop.