Aki, a reincarnated person, is expelled from the Viscount Guinas household with the scornful advice to just go eat some grass by the roadside. His skill, deemed worthless by his family, is called Plant Eater, an ability that seemingly only allows him to consume vegetation. Far from being a punishment, Aki views his expulsion as a welcome liberation from the constraints of noble life, giving him a true chance to enjoy his second existence.

After leaving his former life behind, Aki ventures into a forest where he encounters legendary mythical plants, including a leaf from the World Tree. Upon consuming these extraordinary flora, his seemingly useless Plant Eater skill awakens in spectacular fashion. His status amplifies dramatically, and he acquires a new ability called Absorption. These powers allow him to not only eat any plant but also to gain unique strengths from them. He soon uses his abilities to rescue an elf girl named Saras, a mythical being that the entire nation has been seeking. By saving her, Aki becomes the only human to earn the trust of the elves.

As Aki rises in power, he pushes aside the nobles, royalty, and other influential figures who desperately seek a connection with the elves, eventually becoming a representative existence on the continent. Meanwhile, the Guinas family and his younger brothers who cast him out find themselves in a desperate predicament. Their inability to forge a connection with the elves, now sought after by the entire country, plunges them into ruin as they watch the person they discarded achieve unprecedented success.