The theme of Affirming Willpower and realisation of Love through Self-Denial in Infinity
I think the beauty and wonder in Never 7 is. The courage to end the world that returns to itself after destroing all you have created within it with its help, and the courage to even accept your mortality and unimportance in the inifnity of time, but still love life and love love itself evenso. And perhaps this love can one day break through the eternal chain that fetters Man to eternal despair called Time, and truly be free and love as they wish to. This is also adapted into later works. Never 7 is about rejecting the Wheel of Eternity and choose mortality at the cost of being denied perfection of eternal truth as mortality is not always beautiful and often fails. Ever17 is about enduring that imperfection and sorrow of being alive, but never give up the search for the eternal truth — — which is the joy of being alive even being imperfect — -but it is not about giving up resisting the ugly which would become a form of nihilism and bad Christian / Platonic ideals: it is about resisting that fickle, imperfect and all-denying human destiny with your Will, and Wisdom, and a poetic or tragic passion to realise your love at any cost — at the expense of denying yourself. This is seen in every characters motive and motivation, and their development throughout the story. The obvious one being Takeshi denying his life to save Tsugumi. Tsugumi denying the life that was saved by Takeshi and was the only legacy and memento of him, in order to see him again. Kaburaki giving up his search for “Self”, and giving up trying to find Koko right away and followed a project that defnies his personality, and wish to see Koko, and his diginity as he has to ingratiate himself with Leblich and rise up in ranks for it to come through. Moreover the project was designed by a superior being and all the credits go to him. He followed through with the plan by the supreme being once he identified himself with but now betrays him and tries to take Koko away from him, all this so he can meet Koko — even at the cost of sacrifing his own love for Koko. (love someone so much he can love them through the denial of his love. Agape? Not quite. His love is stronger than that petty thing for idols of unelightened men. The love that persists even at the cost of destroying not only his physical existence (by transforming himself into someone else that took the story away from him, and made him almost non-existent and unimportant. ), his spiritual being (that his whole purpose in life which is “l(fā)ove” — — “l(fā)ove” for Koko must also be denied) and it makes his resolve and sacrifice to save Koko seem pointless and a natural conclusion not part of his effort — -he has to endure the idea he is powerless / impotent, that he cannot save Koko by being himself — he must deny his whole existence in addition to his love too. YouHaru’s denial of her love for Takeshi and the denial of her entire life by giving birth to YouAki is another example. But at the end it is still affirming as the entirety of her existence is able to realise its love for Takeshi in a convoluted way — — through her children and children of those children (but does YouAki fell in love with Hokuto through the karma of their parents and is bound again by the limtis of that karma? or is it something else entirely? the love between Blickwinkel and Koko. or the unrequited love of Shounen towards Koko would argue agains it. Can human WIll surpass even divine design and does the miracles performed by “Wisdom” / Yous in Lemuria a result of sufficient causes or were the seeds that have sown the reasons of being the result of human WIllpower?
The Willpower exhibited by the characters are all very human, and in the most positive sense, very junvenile or boyish. The idea of sacrificing everything for what you truly desire is a proof of innocence and vitality of boyhood. Maybe the whole idea of transcending infinity is being a little naughty and going out for an adventure where there is no hero’s return journey but the ends of the adventure is what the boy is looking for — — away and above life itsef, being fulfilled in the truest existence that is neither matter, spirit or even willpower itself. Peter Pan and Tom Sawyer’s Adventure comes to mind.
Also some music pieces I found that have similiar ideas:

Bartók: For Children, №31 (rev. version 1943)

Chopin’s “Raindrop” Prelude in D flat Major, Op.28 №15

(apparently Chopin was not inspired by actual sound of raindrops. “raindrops” is a name given to the piece by his girl. He said this piece was inspired by something better than poor imitation of sounds — -so it that you, Blickwinkel?)

Franz Liszt: Liebestraum №3 “Love Dream”

PS: Also just something I found by accident that would pique your interest
https://en.wikipedia.org/wiki/Charles_Sirato
“Dimensionist manifesto

In 1936 in Paris, Charles Tamkó Sirató published his Manifeste Dimensioniste,[1] which described how
the Dimensionist tendency has led to:

Literature leaving the line and entering the plane.
Painting leaving the plane and entering space.
Sculpture stepping out of closed, immobile forms.
…The artistic conquest of four-dimensional space, which to date has been completely art-free.”

BTW Young Shounen (Kaburaki) is defnitely the third protagonist. If Takeshi is the cause, Hokuto is the end, Kaburaki is the great effort that connects the two even at the cost of his own destruction. An absolute hero of Dionysian tragedy. ever17