A pact (契約 keiyaku?) is the partnership between two Players during the Game. Neku has 3 possible partners: Shiki, Joshua or Beat (depending on the chapter). Symbolized by the Puck in battles, the pact is not simply an agreement; it is a binding force between two Players, and its benefits are vital to their survival in the Game. These benefits include the ability to activate psychs and the prevention of unwanted battles with Noise (except those set upon them by Reapers and Taboo Noise). A Player whose partner is erased has seven minutes to make a new pact before being erased him or herself. As any nearby Player will probably already have a partner, erasure is almost certain. Pacts can also be formed with certain objects, such as Beat with Rhyme's pin. Harrier Reapers may form a pact with another Harrier, and a Puck will travel between them in battle, but often, they will fight alone, presumably making a 'pact' with their own shadow, hence why they are not consumed by regular noise. Additionally, Harrier Reapers may also form pacts with unpartnered Players, as Beat did with Neku (although this was highly unusual). As a consequence, Beat lost his Reaper powers.
A pact is required to activate any psych abilities and protect the Players from unwanted Noise. Without a pact, Neku cannot deal any damage and his only option is to escape from battle. The only exception is in the final battle, where Neku fights alone. Upon unleashing enough damage, the player can 'reform' a pact with a released partner, giving him a light puck. Upon releasing all 3 partners, Neku presumably forms a 4-person pact, allowing him to unleash a powerful attack reminiscent of the Reaper Symbol.
- According to the manga by Shiro Amano, a pact between Players is established by holding hands (as Neku and Shiki did in the first chapter of the manga). However, this is debatable as other kinds of pact (with pins/objects, with own's shadow, etc.) are certainly not viable through holding hands- such as how Beat made a pact with Rhyme's pin (Pin 262). Still, the basic rule to form a pact might be to simply touching each other, regardless of hand or any other part of the pact maker's body.
- No indication is made in-game about the exact requirements for pact formation. However, when Neku formed pacts with Shiki and Beat, both Players explicitly stated that they wished to engage in a pact on Day 1 of their respective games. Neku's pact with Joshua, however, breaks this convention; Neku is surprised by the formation of a pact and offered no consent.