Introduction

Welcome to Cocoro Session!

Bordering the reality that we know, there grows a world full of mystery. The people of this world each carry a Beat that flows through their Heart, and their Heart only. These lie at the origin of the owner’s very core, and embody their way of life.

These Heart Beats cannot be heard by normal people; those who can hear Heart Beats are only the musical spirits known as Songspirits, the Soul Mates who partner with them, and the monsters who consume Heart Beats known as Soundsiphons.

“Hatsune Miku TRPG: Cocoro Session” (from here on referred to as “Cocoro Session”) is a Tabletop RPG in which you borrow the power of Songspirits to save those whose Heart Beats have been consumed.

Led by a Songspirit, everyone journeys into the dungeons born in the hearts of these victims and battles to overcome the obstacles and Soundsiphons connected to the incident.

Whether or not you will be able to overcome the Soundsiphons and save those who have lost their Heart Beat will be determined by your efforts.

Prepare for your adventure firstly by reading this rulebook. You don’t have to memorize all of it, but reading it from start to finish at least once is a good idea.

After that, find some friends to play Cocoro Session with, and let your adventure begin!

Terminology

• nD6: Roll n dice, and add them up for your total. For example, if it says 1D6, roll 1 die and use the number rolled. In the case of 2D6, roll 2 dice and use their total.
• D66: Roll 2 dice, and use the smaller number in the tens place, and the larger number in the ones place to get a number between 11~66. This is a special way to roll.
• []: Encloses special data about playing the game. For example, used to list your character’s Ability Scores, HP, Desires, Musical Numbers, and Applications.
• (): Encloses formulas. In Cocoro Session, if the result of your calculations is a fraction, be sure to round down before writing it down!
• Phase: Phases are the largest division of play time: the Introduction Phase lasts from when a character is introduced to when they set out on their journey, the Adventure Phase lasts for the entirety of the character’s journey, and the time spent fighting a significant enemy is the Final-Boss Phase.
• Scene: A smaller division of play time, Scenes are divided based on important occurrences during the game, starting with the characters’ introductions.
• Round: The division of play time used to divide up battles, Rounds manage characters’ actions. Each character gets their own turn every Round.
• GM: An abbreviation of “Game Master”, the GM prepares game scenarios, enforces rules, roleplays characters, and tells the story.
• Players: Through their Songsmith characters, the players participate in the game and challenge the scenarios set forth by the GM. Each player can only control their own character.
• PC: An abbreviation of “Player Character”. In Cocoro Session specifically, all PCs are Songsmiths.
• NPC: An abbreviation of “Non-player Character”. All characters other than the PCs, including other Soul Mates, Songspirits, human friends, victims, and Soundsiphons, among others. They are all created and controlled by the GM.
• Character Sheet: Records information regarding a character, such as their name, appearance, and abilities. You make a copy of the blank sheet and fill it in for each individual character.
• Scenario: Records of all data needed to run a session. Prepared by the GM.
• Playsheet: Used to record data on Soundsiphons and keep track of resources such as Timbre. A blank copy can be copied and filled out as many times as needed.
• Timbre: Within the Heartacombs—in which music has been lost—every time a PC acts alongside a Songspirit, the music begins to return. Timbre points represent this. By accruing enough Timbre, Soul Mates can perform special songs known as Numbers.
• Threat: Data on Soundsiphon. Used to make the PCs suffer.
• Tables: Tables in which dice abbreviations such as nD6 or D66 are written can be used to determine things at random. To use these, roll the designated die, find the corresponding spot on the table, and use the data within. Simple!
• Pathos: The 🎵 mark on the Character Sheet represents this. When a character receives stress, add a check mark.

Necessary Materials

The following items are necessary to play the game:

• Dice: 4-6 six-sided dice per player
• Writing Implement: One per participant
• Character Sheet: One per participant
• One playsheet
• 5 Timbre counters
• 6 Masking Cards
• Handbook

Playing Cocoro Session

Cocoro Session is a Tabletop Game in which you explore a fantasy world through talking and rolling dice. You go on an adventure by acting out the character you create, otherwise known as Roleplaying. Of course, while we say acting, it is not as though this is a formal performance—it is sufficient just to think about what your character would do in any given situation and communicating that to your fellow peers.

The following Rules section details how to best enjoy Cocoro Session. However, in a freeform medium such as Tabletop RPGs, the possibilities regarding what you can do are endless, and so you may encounter situations that are not covered by the rulebook. In situations like this, feel free to decide how to precede based on everyone’s preferences to make the game as fun as possible for all—you can even make changes to the existing rules and pre-established setting if desired.

Additionally, the GM has the final say in any dispute with regards to rules of play. Every decision should be made on a case-by-case basis, and so the solution to any given problem will not always be the same; a GM’s decision regarding any particular rules may change even within the span of one session depending on the circumstances. The ultimate goal is to have fun, so try to make your decisions with this in mind.

Every player should ultimately respect the GM’s decisions.