user567: Sokushinbutsu
Sokushinbutsu (即身仏) are a kind of Buddhist mummy.
In Japan, the term refers to the practice of Buddhist monks observing asceticism to the point of death and entering mummification while alive.
Mummified monks are seen in a number of Buddhist countries. Only in Japan are they believed to have induced their own death by starvation.
There is a common suggestion that Shingon school founder Kukai brought this practice from Tang China as part of secret tantric practices he learned.
During the 20th century, Japanese scholars found very little evidence of self-starvation of Sokushinbutsu.
Emperor Meiji banned this practice in 1879, and assisted suicide—including religious suicide—is now illegal.
It says self-starvation and death by starvation.
So does it considered "Nirvana"?
What would Buddha's aspect of self-mummification be?

user23991: The Buddha specifically rejected that kind of self mortification. In fact the first Buddhist monks were ascetics he had previously practiced that extreme asceticism with. After leaving them and achieving enlightenment he sought them out and taught them a "middle way" instead. Their first reaction at seeing him looking healthy and relatively well fed was disappointment at him giving up their idea of the proper spiritual life.
https://www.accesstoinsight.org/tipitaka/sn/sn56/sn56.011.than.html

567: <p><a href="https://en.wikipedia.org/wiki/Sokushinbutsu" rel="nofollow noreferrer">Sokushinbutsu</a></p>
<p>Sokushinbutsu (即身仏) are a kind of Buddhist mummy.
In Japan, the term refers to the practice of Buddhist monks observing asceticism to the point of death and entering mummification while alive.
Mummified monks are seen in a number of Buddhist countries. Only in Japan are they believed to have induced their own death by starvation.</p>
<p>There is a common suggestion that Shingon school founder Kukai brought this practice from Tang China as part of secret tantric practices he learned.<br />
During the 20th century, <strong>Japanese scholars found very little evidence of self-starvation of Sokushinbutsu.</strong></p>
<p>Emperor Meiji banned this practice in 1879, and assisted suicide—including religious suicide—is now illegal.</p>
<p>It says <strong>self-starvation</strong> and <strong>death by starvation</strong>.<br />
So does it considered &quot;Nirvana&quot;?<br />
What would Buddha's aspect of self-mummification be?</p>
 23991: <p>The Buddha specifically rejected that kind of self mortification. In fact the first Buddhist monks were ascetics he had previously practiced that extreme asceticism with. After leaving them and achieving enlightenment he sought them out and taught them a &quot;middle way&quot; instead. Their first reaction at seeing him looking healthy and relatively well fed was disappointment at him giving up their idea of the proper spiritual life.</p>
<p><a href="https://www.accesstoinsight.org/tipitaka/sn/sn56/sn56.011.than.html" rel="nofollow noreferrer">https://www.accesstoinsight.org/tipitaka/sn/sn56/sn56.011.than.html</a></p>
