The connecting record
shownJujutsu Kaisen
Maki Zenin killed Naoya Zenin in Jujutsu Kaisen.
Not the man. She beat him at the estate and walked away, and her mother stabbed him in the back afterwards. What Maki kills is the cursed spirit he comes back as.
What each of them is ranked on
The killer · Maki Zenin · rank 15
Twins in this setting count as one person and split one allotment of jujutsu, and her sister took the innate technique and nearly all the cursed energy. What the sister's death removed was the last of Maki's own — and the Heavenly Restriction that residue had been sitting on top of came up whole. She left the Zenin estate with most of its sorcerers dead behind her.
shownJujutsu Kaisen 0 · ch. 3
Fights among the school's defenders at Jujutsu High on the night of the parade.
statedJujutsu Kaisen · ch. 149
Twins are treated as the same person in jujutsu, and Mai was born with the innate technique and most of the cursed energy.
statedJujutsu Kaisen · ch. 149
Maki's Heavenly Restriction is her own, suppressed by the cursed energy she still carried.
All 7 citations
shownJujutsu Kaisen · ch. 149
Mai dies producing a cursed tool for Maki.
statedJujutsu Kaisen · ch. 149
After Mai's death Maki has no cursed energy at all.
scaledJujutsu Kaisen · ch. 149
Her physical ability is placed level with Toji Fushiguro's.
shownJujutsu Kaisen · ch. 150
Kills the Zenin sorcerers who come at her at the family estate.
The victim · Naoya Zenin · rank 24
statedJujutsu Kaisen · ch. 111, p. 12-13
Projection Sorcery divides one second into twenty-four frames.
statedJujutsu Kaisen · ch. 106, p. 11-14
Anyone touched by the technique who cannot match its frame rate is frozen for one second.
shownJujutsu Kaisen · ch. 152
Maki's mother walks up behind him at the family estate and stabs him in the back, and he dies without fighting back.
All 5 citations
shownJujutsu Kaisen · ch. 191
Returns after his death as a cursed spirit.
shownJujutsu Kaisen · ch. 198
Maki Zenin kills the cursed spirit he comes back as.
What this does not settle
One death in one work. It is the only place the record puts these two in the same room, and it is evidence about that meeting and nothing wider — not a general matchup, not a rematch, and not a ranking of its own.
The ladder above it is argued from everything either of them has been shown doing; this page is argued from one citation.
Where the two disagree, the disagreement is the point, and it stays visible rather than being resolved by whichever of them happens to be on this page.