Former Krugersdorp schoolboy Morné Harmse had prepared himself well on the morning of the day he ran amok and slashed a schoolmate's throat with a Samurai sword.
The 18-year-old pleaded guilty to murder and attempted murder in the Gauteng South high court yesterday.
He told the judge that he had packed his father's swords and three masks before leaving for school on August 18 last year.
"On the morning of August 18, I packed the masks and my father's swords and went to school. I met Marco at the gate and asked him about a bomb but he ignored me. When we were all together we went to the loo. There, I asked them if they were still in. Marco gave me the bomb, but it didn't work when I tried to set it off," he said.
When the bell for assembly rang, the three boys left Harmse alone in the toilets.
"I put on my mask, smeared my face with black paint, hung one sword on my belt and held another with my hand.
"Outside, my friend and a group of kids laughed at me. I swung the sword and cut one of them in the neck," he said.
He killed Jacques Pretorius, 16, by slashing him on the back of the neck.
Pretorius died on the scene while other pupils tried to perform first aid on him.
Stephanus Bouwer, another pupil, was injured in the leg and face.
He was saved by two school employees Sam Manamela, 43, and Joseph Kodisang, 26, who grabbed Harmse and were injured during the process.
Pretorius' family said yesterday Harmse had saved them the trauma of listening to the gory details by pleading guilty on all charge s.
Leonie Pretorius, the aunt of Harmse's first victim, said seeing the killer was very emotional, especially the fact that he showed no remorse and never once apologised for what he did in his confession.
"No I will not forgive him. We are pleased that he pleaded guilty, at least he saved us the trouble and trauma of having to be reminded throughout the trial about Jacques' death.
"Whatever sentence he gets, it won't bring Jacques back," said the tearful woman.
Harmse, dubbed the School Ninja, will be sentenced on June 15.