Furiten: a complete hand can still need a self-draw.
Furiten stops you winning from another player’s discard. It does not stop a self-drawn win. The key is to check your entire wait, not only the tile just discarded.
Ron uses a discard. Tsumo uses your own draw.
In Riichi, ron claims another player’s discarded tile to complete your hand. Tsumo wins using the tile you drew yourself. Both require a legal winning hand, including a yaku.
Furiten is a restriction on ron. It does not remove your tiles or end the hand. If you draw a tile that legally completes your hand, you can still win by tsumo.
One discarded wait blocks the whole wait
Imagine a closed hand with three complete groups, a pair, and 6–7 circles. Either 5 circles or 8 circles completes the last sequence. You previously discarded 5 circles.
That discarded five makes the hand furiten on both waits. You cannot ron on an opponent’s 8 circles, even though you never discarded an eight. Tiles called away from your discards still count as your past discards.
Complete characters sequence
Complete bamboo sequence
Another bamboo sequence
Your pair
Unfinished sequence
Previously discarded by you
Both waits blocked for ron
Can you remove discard furiten?
Before riichi, you may change your hand so that none of the tiles completing the new shape appears in your own discard history. That removes the restriction caused by your own discards. Simply drawing another tile does not clear it while the same discarded wait remains.
After declaring riichi, your hand is normally locked. If your declared wait is furiten, aim for a legal self-drawn win. Declaring riichi does not erase your discards.
Passing a completing discard also matters
Letting a discard that completes your shape pass can make you temporarily furiten, even when the completed shape lacked a yaku. This restriction lasts until your next draw. Do not assume that passing one player’s discard lets you claim the same tile immediately from the next player.
After riichi, passing a legal ron makes you furiten for the rest of that hand. A legal tsumo remains possible. The table checks these restrictions before offering a win.
When a win button is missing
Check whether the hand is actually complete, whether it has a yaku, and whether furiten blocks ron. Dora and red fives add value, but do not count as yaku.
Furiten belongs to Riichi rules. Do not carry it over to Hong Kong, Sichuan or Chinese Classical. Read the rules of the table you joined.
For defence, a tile type an opponent has discarded cannot give that player a ron win. This says nothing about the other opponents: they may still win on it.