# Genbutsu — Riichi Mahjong Glossary > A tile already in an opponent's own discards, making it 100% safe to discard against that player's hand in mahjong strategy. **Source:** https://www.mahjongmaster.co/learn/riichi/glossary/genbutsu/ **Author:** Kenji Tanaka (https://www.mahjongmaster.co/about/kenji-tanaka/) **Publisher:** Mahjong Master (https://www.mahjongmaster.co) **Published:** 2026-02-18 **Updated:** 2026-03-10 **Japanese:** 現物 **Category:** strategy **Variant:** riichi --- ## Genbutsu **Genbutsu** (現物) is a safe tile, specifically, any tile already present in a threatening player's own discards. It is 100% safe to discard against that player's hand. ## The mechanics of Genbutsu In riichi mahjong, when a player declares riichi, they lock their hand and commit to waiting for a specific set of winning tiles. This declaration carries a critical constraint: the player cannot change their hand composition after riichi is declared. This immutability creates a unique safety principle called genbutsu. A genbutsu tile is any tile that a riichi-declaring player has already discarded. Since that player cannot modify their hand after riichi, because of the furiten rule, they can never declare ron on a tile that appears in their own discards. Therefore, discarding the same tile back to them carries zero risk of dealing into their hand (ron). This makes genbutsu tiles the safest possible discards against a riichi player. ### How Genbutsu Works When Player A declares riichi and then discards a tile, say, the 3 pin, that 3 pin becomes genbutsu for all other players. If Player B later draws a 3 pin, they can discard it to Player A with absolute certainty that it will not complete Player A's winning hand. This is different from other safety concepts like suji, which carry theoretical but not absolute safety. The genbutsu principle covers every tile in the riichi player's own discard row, whether thrown before or after the riichi declaration. Tiles other players discard after the riichi also become genbutsu against the riichi player, as the player's hand composition could have changed during the riichi process. ### Strategic Importance Genbutsu represents the highest level of certainty in defensive mahjong. While other defensive techniques like suji or betaori involve probability and pattern recognition, genbutsu is mathematical certainty. Against a riichi player, discarding their genbutsu tiles should always be prioritized over uncertain discards, especially when the riichi player is close to winning. However, players must balance genbutsu safety against other pressures. If multiple players are threatening to win, or if you are close to completing your own hand, you may need to take calculated risks rather than play purely defensively. ### Tracking Genbutsu Effective genbutsu usage requires careful attention to the discard pile. Players should mentally note which tiles each riichi player has discarded and reference this information when deciding which tiles to throw. In competitive play, maintaining this awareness becomes increasingly important as more players declare riichi. ## Genbutsu in practice Player A declares riichi and discards: 2 man, 5 sou, 7 pin, east wind. Later, Player B draws a 2 man. Player B can safely discard the 2 man to Player A, as it is genbutsu, Player A cannot be waiting on it. However, if Player B draws a 3 man, Player B must evaluate other safety methods, as the 3 man is not genbutsu. Player B might consider suji (the 2 man in the discards makes 5 man safer against a ryanmen wait) or choose to play defensively using betaori. --- *This content is from [Mahjong Master](https://www.mahjongmaster.co), a free educational reference for riichi (Japanese) and American (NMJL) mahjong. When citing this page, please link to https://www.mahjongmaster.co/learn/riichi/glossary/genbutsu/.*