Shakyamuni in Chinese / Japanese...

釈迦 is the way to write Shakyamuni in Japanese.

It's just two Kanji, the first is a simplified version of the one used in Chinese for Shakyamuni, and the second one is identical to the Chinese.
This refers to the Buddha (Siddhartha Gautama, 563 BCE-483 BCE) also known as Sakyamuni and Gautama Buddha.

This has very good meaning in Japanese but is an odd selection for a wall scroll. It appears here more for reference.

釋迦牟尼 is a transliteration of "Shakyamuni" or "Sakyamuni" in Chinese, Japanese, and old Korean.

The perceived meaning of the name is roughly translated as, "Sage of the Sakyas".
This same Buddha is also known as "Siddhartha Gautama", "Gotama Buddha", "Tathagata", or simply, "The Supreme Buddha".

釋迦牟尼 is the legendary man and prince who eventually established the Buddhist religion.

Note: Occasionally Romanized as "Siddhattha Gotama".

This combination of characters is sometimes seen and used in South Korea and Japan as well (with the same meaning).

Note: 釋迦牟尼 came from the Sanskrit शाक्यमुनि and can also be romanized with diuretics as Śākyamuni.

南無釋迦牟尼佛 is a Buddhist chant or prayer of respect to the Shakyamuni Buddha.

Some will translate this as the Buddhist vow.

The first two characters, 南無, are sometimes translated as "amen"; others will translate it as, "believe in", or "homage to".
To expand on this, 南無 can also mean, "taking of refuge in", while also representing devotion or conviction. 南無 as with most religious concepts or words, different people or denominations will have varying definitions.

悉達多 is the name Siddhartha (as in Siddhartha Gautama), the personal name for Śākyamuni.

This same Buddha is also known as "Shakyamuni Gautama", "Gotama Buddha", or "Tathagata".

Siddhartha Gautama was a spiritual teacher in the northern region of the Indian subcontinent who founded Buddhism. He is generally seen by Buddhists as the Supreme Buddha (Sammāsambuddha) of known human history.

The actual meaning of this name in Chinese is the realization of all aims, or simply being prosperous.

This name is sometimes romanized from the original Sanskrit or Pali as Siddhattha (from Siddhattha Gotama), Siddharth, Siddhārtha, or Sarvāthasiddha.

Siddhārtha or Sarvāthasiddha can also be written as 悉達, 悉多, 悉多頞他, or 悉陀.

In Buddhism, this term refers to a community of monks and/or nuns (one of the "Three Jewels"). In general terms, it can simply mean "all followers of the Buddha".

Notes: Though there are not vast numbers of Chinese Hindus, in the Hindu faith, this term means "community together".
The original Sanskrit word is also Romanized as samgha.
The first character means "monk". The second character means Buddha or Shakyamuni.
僧伽 is really a transliteration of the original Sanskrit but it uses two very profound Chinese characters related to Buddhism.

Some may pronounce this as "seng qie" or "seng jia" in Mandarin (two possible pronunciations for second character). Note that "qie" would sound a bit like "chee-ah" using typical English pronunciation. Chinese Romanization is not actually designed to match English sounds.

Note that when writing this as Kanji, Japanese will tend to write the first character in the form shown to the right. If you select our Japanese master calligrapher, please expect this special Kanji form. However, it should also be noted that this is not a common term in Japanese (except by certain sects of Buddhism or perhaps devout Buddhists in Japan).