Over the years, Tobirama Senju had indeed been researching forbidden techniques, but everyone supported him because he was doing it for the village.
Since some forbidden techniques could cause energy explosions during testing, the Research Base had been spread across several sites outside the village.
Hashirama Senju knew about this.
Most of the testing facilities had been built deep underground. If an accident occurred, they could simply seal the facilities and bury everything inside.
Tobirama Senju had initially learned a great deal about construction from Yanbai, then refined that knowledge and put it to extensive use.
Most of the researchers underground did not need to leave the base often. They ate, slept, and went about their daily lives in the underground laboratories.
However, after seeing that "moving sack" today, and having Cherry Ink confirm that there was a person inside, Hashirama Senju could no longer remain calm.
Whatever dangerous forbidden techniques Tobirama researched, Hashirama Senju could tolerate them, so long as they were for Konoha, for the shinobi world.
But...
A voice rang out in his heart. Hashirama Senju felt he had to venture beneath this Research Base and find out what was going on.
The existence of Konoha's Research Base was common knowledge. The villagers of Konoha Shinobi Village also knew that its laboratories developed things like Special Cold Medicine and techniques to protect them. Everyone held the institution in high regard and had no objections to it.
However, aside from Konoha High Command, people without clearance did not know the laboratories' exact locations. This was to protect the research, and everyone understood.
Unlike ordinary civilians, members of Konoha High Command had clearance to enter Konoha's Research Base. As the First Hokage, Hashirama Senju naturally had access as well.
An oppressive feeling surged through him like a raging tide