Nakama wo Mamotte Shindara 20-nengo no Onaji Sekai ni Umarekawatta Ken...... demo Ore, Tensei 2-kaime Nanda kedo?

The protagonist, Towa, once died and was reincarnated into another world.

However, in that world, Towa sacrificed himself to protect his friends and died again... and then, he was reincarnated into the same world once more.

Although a considerable amount of time had passed since his death... his former friends, unable to accept Towa's death, had fallen into a deep, dark state of despair.

(Source: Novel Updates)