Botan-chō [牡丹蝶 - ぼたんちょう] is a Mushi variant for 2 players, played in the Kanto region in Japan. It is also known as Kanto Mushi.
The gameplay and Yaku list are identical to Osaka Mushi, but with the addition of the 
Peony with Butterflies card, which is used as a wild card [鬼札 - おにふだ, onifuda] instead of the 
Lightning card. This card is where the game got its name from.
¶ Setup
41 cards of a standard hanafuda deck are used. Remove all Peony and 
Bush Clover cards from the deck, except the Peony with Butterflies card.
Score counters such as chips, go stones, or matchsticks, would be helpful in keeping track of players’ scores. Each player must start with an equal amount of points at the beginning of the game (about 180 points per player), so score counters reflecting those points must be prepared.
Before playing the game, players must decide first how many rounds they should play, and prepare 1-point counters equal to the number of rounds in the game. They will be used as round counters (banko) during the game. In addition, a 1-point bonus would be given to a player every time they won a round.
¶ Distributing the Initial Cards
Nine cards are distributed to each player, and five to the table. While there is no required method for this distribution, it is common for the dealer to give three to the table, three to their opponent, and three to themself, then two to the table, three to their opponent, and three to themself, and then three again to their opponent, and finally three to themself.
The remainder of the deck is placed face-down to form the draw pile.
If 4 cards of the same suit are dealt to the field at the beginning of a round, a misdeal is declared and the same dealer shuffles and distributes cards once more.
¶ Botan-chō card Rule
The Peony with Butterflies card is considered the wild card (onifuda) in the game, and can be matched with any card regardless of its suit.
¶ Botan-chō in hand
The Peony with Butterflies card in a player’s hand can be used to capture any card on the field, regardless of its suit. It can even be used to capture 3 cards of the same suit on the field at once!
¶ Botan-chō drawn from the pile
If the Peony with Butterflies card is drawn from the draw pile, it must be used to capture any card (or 3 cards of the same suit) on the field. In other words, it cannot be discarded onto the field without capturing anything.
¶ Botan-chō on the field (Onitsuki)
If the Peony with Butterflies card is dealt onto the field, it can be captured during a player’s turn if they want to (it can be captured using any card in hand or the card from the draw pile). However, the player is not allowed to discard a card onto the field while the Peony with Butterflies card is still on the field; if it can’t capture any other card on the field, it must capture the Peony with Butterflies card.
¶ End of round leftover card
At the end of the round, the remaining card on the field belongs to the player who used the Peony with Butterflies card.
¶ Scoring
At the end of the round, players score both for the value of their captured cards, and for any yaku (scoring combinations) they managed to collect in their score piles.
The values of each card in Mushi are the standard ones used in Hachi-Hachi and many other games, though the reduction in suits leads to different distributions of those card types.
| Card Type | Value | Number in Deck |
|---|---|---|
| Bright | 20 | 5 |
| Animal | 10 | 8 |
| Ribbon | 5 | 8 |
| Chaff | 1 | 20 |
Note that the Peony with Butterflies card is treated as an Animal card worth 10 points during counting of captured card points.
This means that the total value of the entire deck is 240. Since each player could conceivably capture exactly 120 points, only the points in excess of that are counted. Hence, to calculate one’s initial score for a given round, add up the points for all cards captured, and subtract 120.
Then, the players check for any yaku they formed. The total value of a player’s yaku is paid to them by their opponent, in a zero-sum fashion. For example, if a player has 40 points’ worth of yaku, then they gain 40 points, while their opponent loses 40 points.
In summary, the total amount of points won or lost by the players at the end of each round is
Player's Score = (Player's Total Card Points - 120) + Total Value of Player's Yaku - Total Value of Opponent's Yaku.
The player with the positive score is considered the winner of a round, and the other player must pay the winner points equal to their score. In addition, the winner also takes one round counter as a bonus, which is worth 1 point.
¶ Tie-breaker (Lightning card rule)
Despite being less important than in the Osaka version of Mushi, the Lightning card still has a special role in the game.
If the players’ scores during a round are tied, the player who captured the Lightning card is considered the winner of the round, and gets to take one round counter as a bonus.
¶ Yaku
There are no mutually exclusive yaku here; players score for every yaku they possess!
| Value | Name of Yaku | Composition |
|---|---|---|
| 30 | Five Brights 五光 [ごうこ, gōko] |
     |
| 25 | Three Brights 三光 [さんこ, sanko] |
 Not to be confused with the yaku of the same name in Koi-Koi; this one includes the  Bush Warbler as a pseudo-Bright. |
| 10 | Four Wisterias 藤シマ [ふじしま, fujishima] |
All 4  Wisteria cards.    |
| 10 | Four Paulownias 桐シマ [きりしま, kirishima] |
All 4  Paulownia cards.   |
¶ End of Game
When the last round counter is taken (i.e. the final round is played), the game ends, and the player with the most points is declared the winner of the game.
¶ Bibliography
- https://www.youtube.com/watch?v=ZmB57GBTrnE Omitsu’s gameplay footage of Botan-chō with Jun Kusaba