2017’s To Your Eternity, Volume 1 is the first volume collecting a run of Yoshitoki Oima’s fantasy manga. Originally published as Fumetsu no Anata e, the series has run since 2016 in Weekly Shōnen Magazine.
A remarkable object — Fushi — falls to Earth. Able to mimic other objects, Fushi becomes a rock and then moss. Since neither rock nor moss are self-aware, it does not learn anything from these transformations.
One day Fushi encounters a dying wolf. When the wolf dies, it copies the wolf’s form. This new proves far more educational than its previous forms. Chief lesson learned: while Fushi is immortal, the beings he meets have transient lives.
Warning: if kids dying upsets you, this is not the manga for you. It’s slightly less child friendly than Grave of the Fireflies.