"Daten Sakusen" vol.1-vol.5
Unfortunately, no English translation could be found.
Although not well known even in Japan, it is strongly supported by a small community.
In addition, and unfortunately, the publisher "ura Sunday" recently announced that they will no longer be publishing Daten Sakusen completely, so there is little hope of a story after vol. 5. (Due to the author's health condition).
Despite these circumstances, Japanese fans, including myself, have no doubt that this is a masterpiece.

The protagonist is an immortal being called UNDER. So, as in "Houseki no kuni" and "To your eternity," there is a philosophical problem due to the gap with the general sense of time. The repeated encounters and farewells that gradually develop feelings within the "under" may be similar to "To your eternity".

What makes this work even more interesting is the science fiction worldbuilding. In this world, magic exists, there are several powerful nations, and they are at war all the time. The setting is not clearly defined, but it is probably Central Asia in the near future, in a desolate environment. It is a very harsh place and the area in which humans can live is very small. The politics and power systems are wonderfully constructed. The world itself has depth, and there is a clear set up as to why there are immortal beings, which is hinted at many times.

The cast is excellent. Not only is the development of the main character well drawn, but the supporting cast is also very significant. There is no set partner like in a typical shonen manga, but all the casts have a background and beliefs, and I love all of them. They are at war and will die. Yes, they do.
There are several very sad moments and each time they shine, follow their strong beliefs and die. The protagonist never dies. What I was particularly impressed by is that even the small supporting cast, who appear in only one page, had very emotional moments and made the reader understand them (Ch. 22). The dialogue is very strong and there are many memorable quotes. The cast comes alive and their appearances and structure are natural.

The art style and panel layout are average. The composition is sometimes emphasized by the dialogue.

The relationship between cast, state and ability is so complex that you may not notice it in one read, but you will see their situation and connection as you read it over and over again.

What does immortality bring to a human being and what does death bring to a human being?
The world is always absurd and irrational.
I really love it. Even if I can't read the rest of the story in the future, it will always remain my favorite work.
Sorry for my bad English!