The name Ultimate Truth in Chinese / Japanese...

極真 is the Japanese title Kyokushin.

The literal meaning is “great truth” or “ultimate truth.” However, 極真 is usually associated with the style of stand-up, full-contact karate, founded in 1964 by Masutatsu Oyama (大山倍達).

Practitioners of the Kyokushinkai Karate follow a philosophy of discipline and self-improvement.

真如 comes from the Sanskrit and Pali word often romanized as “tathata” or “tathatā.” Originally written, “तथता.”

It's a Buddhist term often translated as “thusness” or “suchness,” but this does not explain it.
A better explanation may be “the ultimate nature of all things” or “ultimate truth.” However, this gives it too strong of a feeling. This concept is sometimes described as being in awe of the simple nature of something - like a blade of grass blowing in the wind or ripples on water. It is what it is supposed to be, these things follow their nature. Amazing in their mundane simplicity.

Every sect of Buddhism will have a slightly different flavor or explanation, so don't get fixated on one definition.

Notes: Sometimes Buddhists use the word dharmatā, a synonym to tathatā.

In Japan, this can also be the female given name Mayuki, or the surname Majo.

勝義 is a Buddhist term that can mean ultimate truth, beyond description, that which surpasses mere earthly ideas, superlative, or inscrutable.

In Japan, this can also be a given name romanized as Yoshitomo.

眞智 can mean the wisdom or knowledge of ultimate truth.

眞智 is also the absolute knowledge of the non-thing or that which is immaterial. This makes more sense when you consider that true wisdom includes the knowledge of both the real and unreal, or what is material and immaterial.

In Japan, 眞智 (Masatoshi) can also be a given name.

眞覺 means true and complete enlightenment.

This can refer to the perfect nirvana of the Buddha or the perception of ultimate truth or true awareness of all things (reality and unreality).

真諦 is a Buddhist term that can be defined as the real meaning, the true essence, or the ultimate truth.

This Buddhist term means the superior truth or enlightened truth.

勝義諦 is a realm of understanding that is far beyond worldly truth.

Some will also define this as the ultimate truth.

至眞覺 represents the enlightenment of one who has attained the ultimate truth.

This would be the state of an enlightened or liberated person in the context of Buddhism. A goal that all should want to attain and aspire for.

精眞 means pure truth or the apprehension of ultimate reality.

波羅末陀 is the Chinese and Japanese way to write the ancient Sanskrit word Paramārtha or परमार्थ which now means the highest truth, ultimate truth, ultimate reality, or fundamental meaning.

Paramārtha is the name of a famous Buddhist monk born in 499 CE. Paramārtha traveled the world (including Cambodia and territories that are now part of China) to spread the teachings of Buddhism by translating scriptures into the local languages so the truth could be understood by the masses.

So, we should all want to be a Paramārtha who brings the ultimate truth, knowledge, and enlightenment to others.

大乘無上法 means the supreme Mahāyāna truth.

This refers to the ultimate reality in contrast with the temporary and apparent. Other translations include “the reliance on the power of the vow of the bodhisattva” or “the peerless great vehicle teaching.”

Note: This may suggest that Mahayana Buddhism, as practiced in China, Japan, Korea, Vietnam, and other regions is superior (with subtle arrogance) to the original Theravada (or old school) Buddhism. Mahayana and Theravada Buddhists generally get along better than Catholics and Protestants, but there have been schisms.

虚実 is a Japanese word that means “falsehood [and] truth” or “fiction [and] fact.”

This concept is used in warfare, gameplay, and martial arts strategies. 虚実 can be a strategy of real and/or deceptive moves. This gets to some Sun Tzu Art of War stuff where in warfare a strategic move is either a real and serious move or it is a deceptive blow.

Let's explore each character in more depth:

虚 was originally written 虛 (there is a very subtle difference in the strokes at the bottom of the character) and means unpreparedness, falsehood, emptiness, void, abstract theory, empty or unoccupied, diffident or timid, false, humble or modest, virtual, or in vain.
In the Buddhist context, 虛 represents the Pali/Sanskrit word “śūnya,” meaning empty, vacant, unreal, unsubstantial, untrue, space, humble, or in vain.
In ancient Eastern/Chinese astronomy, 虛 represents the “Emptiness” constellation (one of the 28 mansions in the sky).

実 was originally 實 in Chinese (they currently write it as 实 in Simplified Chinese) with the meaning, truth, reality, sincerity, honesty, fidelity, and substance.
The Buddhist context is similar, adding real, true, honest, really, solid, definitely, sincere, solid, fixed, full, to fill, fruit, kernel, verily, in fact, the supreme fact, or ultimate reality to the definition.