Japan, Raijin first day cover,

Raijin , I know about it when I was a child by manga such as Yaiba by Aoyama Gosho or some others by Clamps so it is not something stranger to me.

Raijin (雷神) is a god of lightning, thunder[1] and storms in the Shinto religion and in Japanese mythology.

His name is derived from the Japanese words rai (雷, "thunder") and "god" or "kami" (神 shin). He is typically depicted as a demon-looking spirit beating drums to create thunder, usually with the symbol tomoe drawn on the drums. He is also known by the following names:

-          Raiden-sama: rai (雷, thunder), den (電, lightning), and -sama (様, a Japanese honorific of reverence, glossed as master)

-          Yakusa no ikazuchi no kami: Yakusa (八, eight) and ikazuchi (雷, thunder) and kami (神, spirit or deity)

-          Kaminari-sama: kaminari (雷, kaminari, thunder) and -sama (様, master)

-          Narukami: naru (鳴, thundering/rolling) and kami (神, spirit or deity)

Myth

Raijin was created by the divine pair Izanami and Izanagi after the creation of Japan. There is a legend which says the eight lightning gods were charged with protection of the Dharma by the Buddha. This kind of syncretism, called Shinbutsu-shūgō, is not unusual in Japan, even after the 1868 order that formally separated Shinto and Buddhism. Raijin's companion is the demon Raiju. In Japanese art, the deity is known to challenge Fūjin, the wind god.

Some Japanese parents tell their children to hide their belly buttons during thunderstorms. This is due to a folk belief that Raijin is sometimes credited with eating the navels or abdomens of children, and in the event of thunder, parents traditionally tell their children to hide their navels so that they are not taken away.

 This stampset shows the masterpiece of Tawaraya Sotatsu: Wind God and Thunder God (紙本金地著色風神雷神図). 

Wind God and Thunder God (紙本金地著色風神雷神図) is a pair of two-folded screens made using ink and color on gold-foiled paper. It depicts Raijin, the god of lightning, thunder and storms in the Shinto religion and in Japanese mythology, and Fūjin, the god of wind. The screens have no inscription or seal, but its attribution to Tawaraya Sotatsu is not questioned.

It is a particularly prominent work in the Rinpa school because two other of its major figures, Ogata Kōrin (1658–1716) and Sakai Hōitsu (1761–1828), replicated the painting in homage (see Kōrin's version). All three versions of the work were displayed together for the first time in seventy-five years in 2015, at the Kyoto National Museum exhibition "Rinpa: The Aesthetics of the Capital".

Each screen measures 169.8 cm × 154.5 cm (66.9 in × 60.8 in). They belong to the Zen Buddhist temple Kennin-ji in Kyoto, but they are exhibited occasionally in the Kyoto National Museum. They are a National Treasure of Japan.

Thank you so much, Masako!