ISML 2015

ISML 2015 was the 8th edition of the International Saimoe League contest, and the fourth and final year of the Stella / Nova division split.

This was the last edition that used a single round robin format for the entire regular season. Starting in 2016 it was changed to have each period split the contestants into multiple groups of smaller sizes, with each group eliminating the worst characters at the end.

The champions ban rule was introduced this year: previous female champions (Heavenly Tiara) and male champions (Lapis Scepter) were banned from playing in the Main Tournament for eight years after their win. In addition, all female champions, including this year's winner, will compete in ISML's first ever Tournament of Champions, which will take place after the playoffs stage. Defending champion Kotori Itsuka is the only exception: although banned from this year's playoffs, she is allowed to compete in the regular season as a Stella contestant to give her a second chance to win a necklace.

Eru Chitanda won this year's Heavenly Tiara after defeating Yukino Yukinoshita in the final, in what is considered one of the biggest upsets in ISML history. She became the third girl to become ISML champion without winning a necklace (after Fate in 2008 and Kotori in 2014), and was the second consecutive year where such an event has happened. As 2015 champion, Chitanda directly entered the the semi-finals stage of the first Tournament of Champions contest.

In the inaugural Main Tournament for male characters, Raildex representative Accelerator defeated Monogatari protagonist Koyomi Araragi in the final to win this year's Lapis Scepter.

Male Division
A new division dedicated for male characters was introduced this year.
 * Preliminaries format is identical to the one used in the two female divisions: from Eighty (80) to thirty-six (36). The regular season format and gem names used are likewise the same.
 * Males have their own gem awards called "pendants".  After each period (which lasts 7 matches), the top 7 placed males at that time who haven't won the award yet will play in a pendant round.
 * Since there are five periods this year, five pendants will be awarded. The remaining two gems, Sapphire and Diamond, were re-purposed as "Crown" awards, each having their own different set of qualifications.
 * Male division has only one playoff stage -- Top 16 contestants will fight in a single-elimination bracket. They will be played during the female division's Tiara playoffs.

Champions ban rule
All previous champions are banned from participating in the Main Tournament. They will play in an exhibition event called the Tournament of Champions (ToC) instead.
 * The ban lasts 8 years, starting from the year after they won the championship. Once the ban period is over, a champion may play in the Main Tournament again.
 * 2014 winner Kotori Itsuka is a special case: As a defending champion and Stella Division contestant, Kotori is allowed to play in the regular season, contend for necklaces, and play in this year's Tournament of Champions at the same time. However, she is still banned from playoffs due to her champion status.
 * Male Exhibition winners from 2011-2014 (Lelouch vi Britannia, Kirito, Houtarou Oreki, and Hideyoshi Kinoshita) are retroactively given the champion status as well. However, they will not play a ToC because there are not enough members for such a contest yet.

Seeding score
The 2015 edition saw the staff invent a new method of determining playoff matchups for the surviving players. Instead of using regular season rank, they used Seeding score (SS). It is calculated as follows:
 * Win: Your Current score + (Opponent's current score * Percentage) 
 * Loss: Your Current score - (Your Current score * Percentage)


 * Example: Goku has a seeding score of 420.69 before the 35th / final regular season match, and his opponent  Saitama has a score of 666.66.
 * If Goku wins, his seeding score will rise to  420.69 + (666.66 * 0.35) = 654.021. If Goku loses however, his seeding score will drop to  420.69 - (420.69 * 0.35) = 273.4485 instead, and Saitama's score will increase to  666.66 + (666.66 * 0.35) = 899.991.

Divine Circlet Replaces Jewelries
Jewelry exhibitions (aka consolation gems) were abolished this year; the Divine Circlet replaced this award.
 * Consolation gems (anklet, bracelet, earrings etc.) are discontinued. Instead, bottom-ranked girls will play three qualifiers held concurrently with the necklace rounds, from aquamarine until ruby.
 * The top finishers of each qualifier and one second-placed player with the highest votes will advance to a single-elimination bracket, which is held at the same time as the second phase of the playoffs. The winner of that bracket wins the Divine Circlet consolation prize.

Nominations
ISML 2015 Archive link.

Qualified
Nova

Stella

Male division

Did not qualify
Nova

Stella

Male division

Preliminary Rounds
ISML 2015 Archive link. All preliminary round formats apply to all divisions (male and female).

Elimination Rounds
Eighty (80) characters from each division (Nova, Stella and Male) will play a series of elimination rounds to determine the thirty-six (36) characters who will advance to the regular season. Voters may choose up to 2 characters per group. This voting format applies to all elimination rounds.
 * Round 1: 80 players. 8 groups, each with 10 characters (8x10 groups). Bottom 2 from each group are eliminated.
 * Round 2: 64 players. 8x8 groups. Bottom 2 eliminated.
 * Round 3: 48 players. 6x8 groups. Top 2 advance to regular season.
 * Round 4: 36 players. 6x6 groups.  Top 2 advance to regular season.
 * Round 5: 24 players. 4x6 groups. Top 3 advance to regular season, the rest are out.

After each round, characters will be redrawn into different groups using these criteria:
 * 1) Average of all votes earned throughout preliminaries
 * 2) Group position in previous round
 * 3) Nomination ranking

All rounds last for two match days except round 5, which last for one day instead.

Seeding Rounds
Seeding rounds determined each contestant's schedule for the entire regular season. These rounds started in Round 4 of the elimination rounds, and continued for two more rounds, coinciding with the Winter seasonal schedule.
 * Format: All groups consist of six members. Vote up to 2 characters per group.

Round 1
Held during Prelims Elimination Round 4.

Round 2
Held during Prelims Elimination Round 5.

Qualifications & Format

 * Necklace: Three highest-placed girls from Stella and Nova at the time, plus a fourth-highest player from either division, determined by Regular season tiebreaker criteria.
 * Pendant: Top 7 highest-placed males at the time.
 * Gem winners are banned from participating in further gem rounds.

Format: Modified First-Past-the-Post Voting '(PSAO in period / 3) + Vote percentage = Final score. '
 * Voters choose up to two contestants out of each group (male and female).
 * After the match ends, the scores are calculated using this formula:
 * PSAO: Point-weighted strength of Schedule vs. all opponents
 * The contestant with the highest final score wins the necklace (female) or pendant (male).

Topaz


Sapphire Crown (Male)
Special round: The award is given to the player with the highest seeding score at the end of the regular season. Below is a list of eight players with the highest seeding scores.

Diamond Crown (Male)
Special round: This round consists of four Male exhibition winners, and the remaining three are chosen from the highest-ranked players who haven't won a pendant nor appeared in the topaz pendant round.

Voters can choose up to two contestants from this group. The player with the most amount of votes wins, no calculations required.

Format
= (Votes for / Votes against).
 * Each division has 36 contestants. They are gathered into a single large group, where each contestant plays the others once (a single round-robin system) for 35 matches. These matches are further subdivided into 5 periods, each having 7 matches. The top 16 finishers will advance to the playoffs.
 * Players are ranked by points earned over the course of the regular season: 3 points for a win, and 1 point for a draw.  A loss adds points based on the formula
 * Example: Player A wins against Player B with a score of  6969 - 4200. While Player A gets the 3 points, Player B won't get nothing for his loss; instead he gets ( 4200 / 6969 ) = 0.603 points (rounded to the nearest thousandths).

If there is a tie among two or more players, they are broken in the following order:
 * 1) Wins
 * 2) Head-to-head record 
 * 3) Higher Point-weighted Strength of Schedule of All opponents (PSAO) - basically: the total of your opponents' points times a percentage.
 * 4) Higher vote difference (VD)
 * 5) Total votes earned (VF)
 * 6) Staff selection

Seedings
Seeding score
 * The Seeding score (SS) is used to determine the first round match-ups of each division. It is calculated as follows:
 * Current score ± (Current score * Percentage) = Seeding score.

Nova

Stella

Male

Phase 1
Swiss-system format.
 * Round 1's matches are decided by seedings: 1v16 / 8v9 / 4v13 / 5v12 / 2v15 / 7v10 / 3v14 / 6v11
 * After each and every round, players will be matched up against players with the same record as theirs.
 * The tournament continues until a set amount of rounds has been played. In ISML's case, it's 4 rounds.
 * After 4 rounds have passed, players will be ranked in this order:
 * Wins
 * Quality wins (QW) - wins against players with the same or better record than theirs
 * Regular season rank


 * Top 8 of each division will advance to Phase 2, while the rest will say goodbye to their championship dreams.
 * First-placed girl of each division is awarded the Sapphire circlet (Nova) or Diamond circlet (Stella).

Nova playoffs (Sapphire)


Phase 2

 * Single-elimination bracket.
 * Bracket order for males: 1v16 / 8v9 / 4v13 / 5v12 / 2v15 / 7v10 / 3v14 / 6v11.
 * Bracket order for females:
 * N1 vs S8, S4 vs. N5, S2 vs. N7, N3 vs S6
 * S1 vs. N8, N4 vs. S5, N2 vs. S7, S3 vs. N6
 * All losers except the runner-up play consolation matches to determine their final rankings.
 * Winner of the final match claims the Heavenly Tiara (female) or Lapis Scepter (male) and declared as the champion.

Winner's Gallery
Necklace & Tiara