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.
Peace of the Kami: ...Negate all current effects on it from other players' cards... Suck the Marrow: ...Give the target a -1F/-1C Poison token. Lose 3 Honor. Until the game ends, after each Events Phase begins, give the target a -1F/-1C Poison token.
Will Peace of the Kami end the ongoing effect of Suck the Marrow, or is it just negated for the turn with the marrow-sucking continuing in the next Events phase?
Only for the current turn. The marrow-sucking will resume next turn.
See here: If a continuous effect or a current ongoing effect that has been prevented is still in effect when the prevention effect ends (for example, when the duration of an ongoing prevention runs out, or a card with a continuous prevention effect leaves play), the prevented effect re-asserts itself.