It doesn't seem like he got one as a gift? He just picked up a few herbal plants since he felt that they'd make his garden look a bit more the part, given his public face as an alchemist. But, basically every herbal plant is the progeny of the world tree, its spores travel far and wide through the atmosphere and grow all over the place. It is just that those plants grow in far too mana deficient environments to properly express that heritage. But say someone decides to water one with an S class potion? That changes things up a bit. Look back on page 17 of chapter 1 and notice that there's a tree in his yard, and that he has that little caterpillar buddy (Imosuke). Imosuke isn't entirely unrelated to the tree at this point, but it's the potion that caused the tree start its development.

Bascially MC's bro?
If I remember right he operates one of those magic knight mecha.
Probably even more of a perv, or possibly just more open minded than MC. (Conil finds beautiful boy brothels to be equally acceptable.)

Elitist jerks, have a monopoly on the world tree, and in the past enacted a large scale magic to ensure that there's only ever one at a time. Elf women have their main erogenous zone deep inside, hence the "deep ones" comment back in chapter 1, page 16. It's pretty much impossible for a human to bring them to their true, complete orgasm, which is actually story relevant.

Demon eyes (?) that do real time tracking of arousal levels and erogenous zones. Ki extension of penis to attack deeper than what he can actually physically reach. These are actually pretty good magic sensing/manipulation skills, which means he can actual control a magic mecha extremely well. Although he actually synchronizes too well, such that attacks inflicted on even just the meter high training mecha feedback as pain to his actual body. He takes the state sponsored classes for a while before dropping out because he realizes that they'll never accept a recruit who avoids melee combat and just spams magic missile.