Killua's weapon of choice is a pair of specially designed yo-yos. The yo-yos are extremely durable and heavy, each weighing 50 kilograms (approx. 110 pounds). They are constructed with an unnamed special metal alloy, which is also an excellent electrical conductor. Killua obtains the weapons through his brother Milluki, most likely after exiting Greed Island to retake the Hunter Exam.
The yo-yos are a purple/navy blue color, with the stars being yellow in the 2011 anime. In the manga, the yo-yos are printed with a six-pointed star, or hexagram (✡). In the Greed Island arc OVAs, the hexagram is changed to a pentagram (⛤) or an inverted pentagram (⛧), or yet a five-pointed star (☆). However, later in the Chimera Ant arc, Killua is seen using a yo-yo that has a pentagram. Because Killua has two yo-yos, there is probably one yo-yo with a hexagram design and another with a pentagram.
Greed Island arcEdit
Killua first shows the two yo-yos to Biscuit as part of his preparations for the battle against the Bomb Devils, announcing his will to combine them with his Nen ability. Being the first time he uses them in combat, he experiments during his fight with Sub, doing things like running electric currents through them as a form of attack, and in turn defeating him.
Chimera Ant arcEdit
Killua uses one of his yo-yos to grab Ikalgo before the latter falls in the Underground Lake, where his blood-frenzied Chimera Ant subordinates would tear him apart. During the infiltration into the Royal Palace of East Gorteau, he obliterates the heads of two insect soldiers (Inzagi and Maenole) with them to save Ikalgo's cover, although this fact leads to Welfin growing suspicious of Flutter (Ikalgo's cover). He later attacks Palm with one of his yo-yos, only for it to be crushed by the reborn woman.
- Despite their weight (50 kilograms each), Killua is often seen pulling them out of his pockets.
- Hexagrams, six-pointed geometric star figures, are used in a variety of religions and cultures including: Islam* (e.g., as the Seal of Solomon); Christianity*; Occultism*; Hinduism/Buddhism/Jainism* (generally in cosmological diagrams, e.g.: as the Shatkona and in the Anāhata symbol); and especially Judaism*, where the hexagram is the symbol used for "The Star of David" (✡).
- Another Zoldyck-related item, the Zoldyck Personal Transmitter, also has the same symbol on it.
- Killua briefly uses his yo-yos during the Hunter × Hunter: The Last Mission movie.
- Killua's yo-yos are similar to the "Serpent Yo-Yos" used by Rinku in YuYu Hakusho. However Rinku's yo-yos are small and have five-pointed stars.