Traveling back thirty years to Conan, intercepting Princess Eri

The two girls' eyes quickly searched the alley, not missing a single corner.

Drainage outlets, garbage heaps, cracks in the corners of walls, discarded cardboard boxes...

Suddenly, Yukiko's gaze stopped on one spot.

It was a sewer grate, made of iron, square, covered in brown rust, and with some signs of damage on the surface.

At first glance, it looks no different from the other grates around it, with the same material, the same rust, and the same inconspicuous appearance.

But one detail made Yukiko's heart suddenly skip a beat.

The comb doesn't seem to be completely covered.

The other grates fit perfectly into the grooves in the ground, with their edges flush with the surface.

However, the gap on one side of this comb is obviously larger than the other side, as if it had been pried up and then carelessly put back in place, without being completely reset.

The gap was about a finger's width, almost invisible in the dim light, but could be seen upon close inspection.

Yukiko held her breath and walked over quietly.

Her high heels made a slight creaking sound on the damp ground, the sound particularly clear in the quiet alley.

The girl crouched down and gently tried to lift the grate.

The comb moved. It was much lighter than I had imagined. Although the rust made it look heavy, it was actually only a thin layer of rust left.

Yukiko used very little force to lift a corner of it.

Below is a dark, gaping sewer.

An even stronger stench hit them, almost making Yukiko let go.

She forced herself to stay awake and looked down.

The sewer is not deep, only about half a meter deep, and the bottom is covered with a layer of murky sewage.

The sewage contained all sorts of random things: withered leaves, cigarette butts, plastic bags, and junk from who-knows-when.

Light shone through the opening and reflected off the water's surface, creating dim patches of light.

And in that sewage, lay something inconspicuous.

A small medicine bottle.

It is made of glass, is transparent, and is about the thickness of an adult's thumb.

It was half-buried in sewage, with only a small bottle cap showing.

The lower part of the medicine had become filthy from contact with sewage, covered with a layer of dark brown, viscous substance.

However, the top half was still brand new, with the words on the label clearly visible, showing no signs of being completely soaked in water.

Clearly, the medicine bottle had just been thrown down the drain not long ago.

Yukiko's eyes lit up, and she instinctively reached out to pick it up.

"and many more!"

Eri grabbed her wrist with such force that Yukiko winced in pain.

"What are you doing!" Yukiko turned around in displeasure, only to find that Eri Kisaki's expression was unusually serious.

Eri Kisaki didn't explain, but quickly took a clean handkerchief out of her pocket.

She unfolded the handkerchief, held it in her hand, and then squatted down, carefully reaching into the sewer to retrieve the medicine bottle.

"If this medicine bottle is really related to Matsuzaka Yuki, it must have her fingerprints on it."

Eri Kisaki explained as she went.
“Touching it directly might destroy the fingerprints. Even if we hand it over to the police, we'll have lost the most important evidence.” Yukiko paused for a moment, then muttered defiantly, “I know that too.”

Her voice was soft, tinged with a hint of guilt and a touch of stubbornness.

Actually, she was so excited that she forgot about it for a moment.

But how could she possibly admit to Eri Kisaki that she hadn't thought things through?

Eri ignored Nozomi's explanation and focused all her attention on the medicine bottle in her hand.

Her movements were light and steady; she used a handkerchief as a pad to carefully pick up the medicine bottle from the sewage.

After the medicine bottle left the water, Eri held it up to her eyes and examined it carefully.

This is a standard prescription medicine bottle, made of brown glass with a screw-on white cap.

The label contains information such as the drug name, manufacturer, usage and dosage.

The upper half of the label was still clear, while the lower half was blurred by sewage, but the key drug name was still legible.

"Digaxin?"

Yukiko leaned closer, read the name of the medicine on the bottle, and frowned slightly.
"What kind of medicine is this?"

Her medical knowledge was limited, and the unfamiliar name of the drug left her completely baffled.

But judging from Eri's expression, she seems to be very familiar with this medicine.

The girl didn't answer immediately; she turned the medicine bottle over and carefully examined the other information on the label.

The production date was six months ago, and the shelf life is still two years.

It doesn't have the patient's name or hospital logo, so it must have been purchased separately from a pharmacy.

“Digoxin belongs to the digitalis class of drugs,” Eri Kisaki finally spoke, her voice low. “It is used to treat heart failure and arrhythmia. Simply put, it is a cardiac stimulant.”

"Huh?" Yukiko was immediately disappointed, her shoulders slumped. "It's not poison. I thought we'd found evidence, but it's just a regular heart medication."

She looked at the small medicine bottle and felt a wave of frustration wash over her.

The excitement they had just felt dissipated almost instantly. If it was just an ordinary medicine, wouldn't all their hard work have been for nothing?
But Eri Kisaki's expression remained serious, even more so than before.

“No.” Her gaze was fixed on the medicine bottle in her hand. “Although it can cure diseases, it is actually almost like poison.”

Yukiko was stunned: "What do you mean?"

Eri Kisaki took a deep breath and slowly explained, "The therapeutic dose and the toxic dose of digoxin are very close. Just a little bit more can cause poisoning."

She paused, then continued.
"If digoxin is overdosed, cardiac arrest will occur within half an hour due to ventricular fibrillation."

Yukiko's eyes widened further.

"You mean..." Her voice trembled slightly, "...that Kosuke Iguchi might have been poisoned to death by this drug?"

“That’s possible.” Eri nodded. “Did the deceased have a history of heart disease? If so, then it would be normal for him to take digoxin. The question is the dosage—was it a therapeutic dose or a lethal dose?”

“But…” Yukiko raised a question, “If Kosuke Iguchi died of poisoning, wouldn’t the police’s autopsy have found out? The forensic doctor would know everything by examining the blood.”

Eri Kisaki shook her head: "As I just said, the therapeutic dose and the toxic dose of digoxin are very close."

"If the police test the blood and find digoxin levels, it is very likely that they will simply assume that it is a treatment drug and that the deceased was taking it normally before his death."

"Besides, there was such a conspicuous and suspicious wound on the back of the deceased's neck."

"Anyone who saw that wound would naturally assume it was the cause of death. Who would have thought he was actually poisoned?" (End of Chapter)