Here are the rules in short form:
1) Slice the Makushita banzuke into 15 equal brackets (ms1ms4, ms5ms8 etc.).
2) Pick one rikishi from each bracket.
3) Send your selection via the entry form
4) The deadline is shonichi 8 AM JST.
5) Done.
Here are detailed rules for the ruleminded:
1) You collect win points for your picked rikishi, and these win points will be converted into a winloss record. If a rikishi finishes with a MK, you won't get any win points. If a rikishi finshes 43, you'll get 0.5 win point for your overall win point tally. A 52 gives you a full win point, a 61 nets 1.5 win points, and a 70 adds two full win points (if a rikishi has an eighth bout, the win points depend on the result of this last bout: e.g. a 53 after 43 adds 0.75 win points; a 44 after 43 is treated like the 43, i.e. with 0.5 WPs). The sum total of win points across 15 rikishi amounts to the winloss record for a player (if necesseary it will be rounded up or down based on banzuke requirements).
2) The player with the most win points gets the yusho. In case of a tie, brackets will be compared pairwise (in descending order down the banzuke) until a winner can be determined.
3) Sansho prizes are awarded as follows (all sansho require a KK):
3a) Shukunsho for the player who picked the yusho winner. In case of a tie, other 70 rikishi will be compared, followed by 61 rikishi in descending order etc., until a winner can be determined.
3b) Kantosho for the player whose rikishi have netted the most wins.
3c) Ginosho: for the player with the most unusual picks  total sum of wins of a rikishi divided by number of players who picked him.
4) A kosho application is not necessary. In case of a single absence the player keeps his/her rank, if possible. The second consecutive kyujo basho will be counted as 0015, and the third kyujo in a row leads to the retirement of the player.
5) Kyujo rikishi: Because there is little time between kyujo announcements and the start of the basho, players are allowed to replace a kyujo rikishi with a 00 rikishi or 01 rikishi until day 2 of the basho (8 AM JST).
6) Promotions (these rules might change):
6a) Ozeki promotion requirements: three KK in a row with at least 31 wins total; Sekiwake rank at the crucial third basho; alternatively, a 3basho cumulative "position score" below 15 (if you finish first, your position score is 1; if you are tied for second place with three other players, your position score will be 3.5 etc.)
6b) Yokozuna promotion: Two consecutive yusho and overall good manners.
