This manga is not bad at all. I give it 8.5/10, rounded down.
Fresh concept, decently executed.
The MC asks a Genie for a little sister. The Genie, in a bind because creating a whole person ex nihilo is super hard, simply becomes the little sister. The MC rejects this, but the Wish must get fulfilled so the Genie just tries harder.
Meanwhile various shady characters starts moving for the valuable Genie, and also we see hints that the MC's little-sister obsession comes from psychological trauma, so maybe healing that is an option to resolve the situation.
The pacing is perhaps a bit frenetic, and the feelings a bit too exaggerated. Also, it would be nice to see some exploration of the whole stuffed-in-a-lamp thing; go into the Genie's backstory instead of treating him as a given.
Some more subverting expectations or reconstructing the concept - or just reaching a satisfying conclusion - would be enough to make me raise the grade a notch.