I look at Ishibashi and the others and they are staring at Lamia with a dumbfounded look on their faces. It's embarrassing to think that I was like this earlier. If I had been like that, I would have been killed easily.

　Perhaps if they are in a state to be completely manipulated by Lamia's mental attacks, they may start fighting each other. We must defeat them before that happens.

　I held my guard up and stared at the lamia. It was about seven meters long, with a thick body for a snake. I could hear it slithering forward.

　To try it out, I activated "Crash Ball" in succession and released D-particle vibration balls in scattered bursts. Lamia seems to be able to sense D-particles and quickly avoids them. The D-particle vibration balls that missed hit the wall and made a deep hole.

　Lamia unleashes a cleaving attack with her tail. Against the tail coming at her with great force, she intercepts it with the Titan Plate by activating "Titan Push".

　The tail was bounced back by the titan plate. The reaction also dragged Lamia's upper body. Having repelled the tail attack, I observed Lamia's upper body.

　He thought that that upper half of his body might be his weak point. Stepping into a ten-meter gap, he activated his seven-fold activated "high blade" and swung the huge blade formed by D-particles toward the eerie upper half of his body.

　Lamia desperately tried to avoid it. However, the blade of the D-particle exceeded the speed of sound, and Lamia was unable to avoid it completely, sustaining a deep wound in her torso.

　The Lamia, writhing in pain, was hit by a high-speed vibrating ball with "Crash Ball II" activated. At the moment of impact, a destructive space three meters in diameter was formed, engulfing the upper half of Lamia's body.

　That was the tome and when the lamia disappeared, the black magic stone and the booklet remained. When retrieved and checked, the booklet was written in new characters, and it was not clear what it was about.

　When I look at Ishibashi and the others, they seem to have come to their senses, although they are wobbly.

What happened?"

'I ran into Lamia. Don't you remember?"

Come to think of it, ...... my head hurts."

Let's go back to the stairs and rest."

　We walked back to the stairs and rested. By then Ishibashi and the others had recovered and seemed to remember what had happened.

If you stumble upon this narrative on Amazon, be aware that it has been stolen from Royal Road. Please report it.

'Ahh, ...... looks like we've been hit by a psychic attack. Dr. Grimm saved our lives."

I didn't expect to run into Lamia there. I thought Lamia was the mid-boss.

　That's right. I had thought that if I was going to encounter Lamia, it would be in the middle boss room. I didn't expect to encounter him as a normal demon.

　The lamia was easily killed, so it seems they are not as innocuous.

If the fifteenth layer is crawling with them, we need some kind of mental defense.

"Haven't Mr. Ishibashi and the others mastered the 'Steel Heart Technique' inscribed on the wall of the second ruin?"

'Is it a mental defense technique?'　None of us can read the sacramental script, so we may be investigating it, but the contents are awaiting deciphering by scholars. Can Dr. Grimm read them?"

Yes, I used the Scroll of Knowledge.

'Hoh, was that a good thing to publish?'

I used to ask the branch manager to keep it secret because I was afraid he would ask me to decipher the text of the Sacred Script. But now that I'm an A-level student, I'm sure he won't be asking me to do so easily."

'Maybe so. But 'steel heart technique'? That's a technique I've never heard of. You'd better register it with the Magical Agency. If you delay, one of the scholars will decipher it and someone else will register it."

Yes, I will. I will."

　I decided to end my search and return to the surface. I left Ishibashi and the others and headed back to the ground.

　It was evening when we returned to the ground. After stopping by the Adventurer's Guild, I reported back to them and told them that the 15th layer was inhabited by lamia, and that it would be dangerous unless they had some kind of mental defense technique.

　Hearing this, Branch Manager Kondo nodded with a serious face.

"Well done for informing me. A lamia, a dangerous demon indeed."

By the way, there was a text inscribed on the ruins in a script I've never seen before, is that being investigated?"

It's called 'temple script,' but we're just starting to study it, so we haven't made much progress."

Have any of the texts found at the site raised any discoveries that would be registered with the Magical Office?"

'No, the Magic Agency hasn't reported it, so it must not be there yet. Perhaps you have discovered it?"

I'm going to register how to make the paint for the shadow puppets and one of the mental defense techniques I mentioned earlier."

'Well, Mr. Grimm, you work fast. You just started surveying the ruins, didn't you?"

As you know, I can read magic and sacramental script.

　The branch manager nodded as he remembered.

I'd like you to decipher the text written in the Sacred Script. Actually, I'd like you to decipher the text written in sacramental script, but it's not the kind of job I'd ask a class-A adventurer to do."

　The branch manager said he couldn't even imagine what the hourly rate would be if he asked a Class A adventurer to do it. I grinned when I heard that.

　After I finished my report, I decided to go to the Magic Agency, but it was already time for the government office to close. When I had no choice but to return home, I found Nezu reading the weekly adventurer in the dining room.

Is that this week's issue?"

'Yes, it is. I read an article about an advanced dungeon in Canada where the lodgerless were out of the dungeon."

　It is a rare occurrence for a demon to go out of a dungeon. Several conditions must be met for a demon to exit the dungeon. First of all, the demons must be without a host.

　There have been a few incidents of demons coming out of dungeons in our history, but all have been without lodging.

So what about the demons that came out?"

It's a white auger. It seems to be a subspecies of the Silver Ogre."

'Wow, some nasty demons came out of the woodwork. Who beat it?"

I'm Isaac Sinclair, Class A. You are the magician in magical attire known as 'Sinclair the Flash'."

　Sinclair is an adventurer with a Class A ranking of 39th. Her combat skills are better than mine, and her weapon of choice is a mythical sword called Arondite.

　I believe that the White Ogre was defeated by a large number of people working together rather than one-on-one, but only the last person to put the tome in the record.

"Were there any casualties?"

Fifty-six civilians and fourteen adventurers died.

　I get a dark look on my face when I hear that. I remembered when I fought the Silver Ogre. If the white ogre had gone out of control at that speed, it was no wonder there were so many casualties.

　As was the case with the basilisk zombies, the Adventurers' Guild tries to defeat the hostless as soon as they appear. If left unchecked, they might come out on the ground.