Heroic Spirit Deck in Yu-Gi-Oh!

"The so-called shadow game can be simply understood as one of the mysteries residing in this world," Mash began to explain in detail while operating the equipment swiftly.

"This world hides a mystery known as the Millennium Seven Items, ancient Egyptian artifacts passed down through history. These items grant their possessors immense dark powers and are essential for initiating the so-called shadow games."

"The dark power needed for the shadow game, huh?" Hoshino pondered, touching her chin. "Why do these human-made artifacts possess dark energy?"

"According to our research, the Millennium Items were initially created to fend off foreign invaders. However, during their creation, the entire village was massacred, and the excessive killing caused the villagers' resentful spirits to inhabit the items." Mash appeared somewhat tense as she explained. "Moreover, the seven items themselves are keys to opening the legendary gates of the underworld."

"The keys to the underworld? Do you mean the underworld ruled by Ereshkigal?" Hoshino recalled the golden-haired, tsundere girl who resembled Rin and appeared during the restoration of the Seventh Singularity, 'Absolute Demonic Front: Babylonia.' "That doesn't sound too terrifying."

"Ah, Miss Ereshkigal..." Mash smiled awkwardly. "While she is indeed the goddess of the underworld in the Age of Gods, this world is quite different."

"You know, Master, in the Age of Gods, the human world and the underworld were physically connected. If you dug deep enough, you could enter the so-called underworld through physical means." Mash explained in detail, using images on the screen. "But whether it's because we're too far from the Age of Gods or due to differences in the world itself, the underworld in this world is a far more terrifying existence. Moreover, it's not Miss Ereshkigal who controls it."

"Then who does?"

"The Great Demon God Zorc!" Mash stretched her hands to the sides of her face and made a playful roar, trying to appear scary but looking rather cute instead.

"Oh, I see." Hoshino twitched her mouth, watching Mash's lively performance. "That does sound a lot scarier than Eresh."

"Ahem..." Mash realized from the snickering behind her that her performance had been less than convincing. "Anyway, if an ordinary person like you, Senpai, were to engage in a shadow game—"

"You would undoubtedly lose!" Mash's serious gaze conveyed that this was no exaggeration. "And in the worst-case scenario, Senpai, you might die."

"Die?" The timid Hoshino shrank back. She had thought this otherworldly card game would be fun, not life-threatening.

"But you don't need to be too scared, Senpai. I was speaking hypothetically about you being an normal person." Seeing Hoshino's fear, Mash smiled reassuringly.

"Am I not an normal person?" Hoshino didn't quite understand.

"As the only Master of Chaldea, the strongest human organization, supported by hundreds of Heroic Spirits, having successfully restored numerous Singularities and ultimately saving humanity from its ends, the Incineration of Humanity—how could you be normal l person?" Mash's voice was filled with pride.

"But that's just the setting of the game. I'm just a normal..." Hoshino was interrupted as Mash gently placed a finger on her lips, shaking her head with a smile.

"You are you, Senpai, no matter which world you're in. Chaldea will always be your strongest support." Mash's warm smile seemed to radiate human kindness, making her appear almost angelic.

"Mash..." Hoshino, looking at Mash and the Heroic Spirits who had followed her out of concern, couldn't help but tear up.

"It's connected, Senpai. The screen is showing the current state of the shadow duel." After a series of complex operations, Mash had finally brought up the live feed of the dark duel on the central control room's large screen.

"Jonouchi? Honda? Why have they all turned into Duel Monsters?" Hoshino exclaimed at the sight on the screen.

"Because everyone's souls have been sealed in their favorite cards," Mash explained. "If it weren't for Medea's help, your soul would have been sealed in my card."

"Then how do we win this shadow game?" Hoshino asked the crucial question.

"Like any normal game, you just need to reduce the opponent's Life Points to zero."

"Phew, that sounds simple. With Yugi's skills, he won't lose." Hoshino breathed a sigh of relief.

Mash shook her head, contradicting Hoshino's assumption. "If this were a normal duel, Yugi would never lose. But this is a shadow game, and the initiator of the shadow game has set rules that are extremely unfavorable to Yugi."

"Extremely unfavorable rules?"

"If a card containing a soul stays in the graveyard too long, the Reaper will take it." Mash resumed her animated explanation. "Once taken by the Reaper, the soulless body will never awaken."

Hoshino swallowed nervously, realizing the disadvantageous rule. No card with a comrade's soul could be sent to the graveyard, meaning even weak monsters like 'Commander' couldn't be defeated.

"Then can't Yugi just keep the cards with their souls in his hand and not play them?" Hoshino thought of a loophole.

"It's not that simple, Senpai. Look." Mash pointed to the screen, indicating the current duel.

Bakura: "Activate Morphing Jar's effect! Discard all cards in both players' hands and draw five new cards!"

The Pharaoh glanced at his hand, relieved to find no soul-bound cards. He discarded his hand and drew five new cards from his deck.

"!!!" Hoshino instantly grasped the situation. If Bakura used Morphing Jar again, keeping soul-bound cards in hand would be even more dangerous.

"What a despicable tactic." Hoshino bit her finger and cursed angrily.

"So, Master, we will now teach you how to counter the shadow game." Seeing that Hoshino understood the situation, Mash continued.

"We? Who else?" Hoshino looked at the crowd behind her, doubting it could be any of them.

"It's me!" A familiar avatar suddenly lit up on the bottom right of the screen.

"The most beautiful, all-powerful genius Da Vinci-chan is here~~"