Buddhism is a religion originating from the Indian subcontinent that follows the teachings of the Buddha.
The Buddha's central teachings emphasize the aim of attaining liberation from attachment or clinging to existence, which is said to be marked by impermanence (anitya), dissatisfaction/suffering (duḥkha), and the absence of lasting essence (anātman). He endorsed a path of spiritual development that avoids extreme asceticism and extreme hedonism called the Middle Way. The Four Noble Truths, accepted by all Buddhist traditions, are aimed at ending saṃsāra-related re-becoming (rebirth) and associated cycles of suffering.
There are considered to be six realms of rebirth: the Gods realm is where devas exist and is the most pleasurable realm of rebirth, the human realm, the demigod realm, the animal realm, the hungry ghost realm, and the hell realm where those with evil karma visit until their evil karma has been exhausted and then they're reborn in a different realm. The liberation from this cycle of existence, Nirvāṇa, is the foundation and the most important purpose of Buddhism. There is no single textual collection for all of Buddhism and its canon is vast and non-definitive. There exists many different Buddhist schools and branches, but the two major schools are Theravāda and Mahāyāna.
Buddhism is one of the most popular religions in Japan, introduced in the 6th century, while it is a minority religion in the United States of America, introduced in the 19th century. The most popular branch of Buddhism in Japan is Pure Land Buddhism, which belongs to the Mahāyāna school of Buddhism.
In TMNT[]
While Buddhism is seldom directly referenced in the Teenage Mutant Ninja Turtles franchise, the central characters—Splinter and the Ninja Turtles—are sometimes revealed or at least implied to be Buddhists.
TMNT Adventures[]
As mentioned in the Teenage Mutant Ninja Turtles Adventures story Turning Japanese, Splinter and the Ninja Turtles are Zen Buddhists. Katmandu is also a Buddhist.
Mirage[]
In the Mirage continuity future story Swan Song, a future Leonardo becomes a Buddhist monk after the death of his lover Raven Shadowheart, eventually advancing to bodhisattva, a Buddhist holy man so enlightened that he was close to attaining Buddhahood himself.
IDW[]
In the IDW continuity, Hamato Yoshi prays to the Buddha for justice for his sons' executions as right before his own execution by the Foot Clan for treason. In The Secret History of the Foot Clan issue 2, a statue of the Buddha doing the Brahma mudrā ("Brahma seal") is seen outside of the temple Oroku Maji and Masato visit to determine if Oroku Saki is Takeshi Tatsuo reborn as Kitsune threatened. The monk they consult tells Maji that children absorb all of their life experiences and are influenced by them. He also states that love is the most powerful and valuable dharma and with it, it's possible to counter Takeshi's evil karma with the non-evil karma Saki may create in his life and reach a balance. In the Teenage Mutant Ninja Turtles: Shredder in Hell mini-series, Yoshi's spirit brings Saki's spirit to Saki's Dream Forest as promised. Buddhism accepts that the human realm is just one of the many realms in existence. Reminiscent of this belief, Yoshi states in issue 1 that there exists many realms of the afterlife and Kid mentions in issue 3 that there are multiple realms for "ascending spirits" and descending spirits. At the Tree of Life, Yoshi tries to convince Saki to abandon all of his desires (taṇhā) and fears and become one with the Dreamer to stop the god using him and his past incarnation as a vessel, the Dragon, from eliminating humanity. Saki chooses not to cooperate with either god and Tang Shen's spirit allows Yoshi to follow Saki on his journey through Hell to guide him to the right course and save humanity. However, this requires Yoshi to sacrifice Nirvāṇa, thus he will be reborn. In issue 4, he returns with Saki to the Tree of Life to strangely find Shen still there. Shen chooses to stop her spirit from ascending, forfeiting Nirvāṇa in solidarity with Yoshi and the two of them resign themselves to continuing saṃsāra. Shen and Yoshi then are reborn in the "earthly realm".
2014 film series[]
In the 2014 film series, it may be implied that Splinter practices Buddhism as he tries to attain complete spiritual enlightenment and Nirvāṇa. However, there are multiple other Indian religions that have a concept of Nirvāṇa and spiritual enlightenment as well.