Trade: SeaHorses Mikawa vs. Koshigaya Alphas

Market context

The Japan B League will host a matchup between SeaHorses Mikawa and Koshigaya Alphas on 2 May at 2:05 AM ET. The current order book on Polymarket reflects a 100% implied probability for resolution, indicating traders are pricing near-certainty that the market will settle to one of the two teams rather than face postponement or cancellation. This extreme probability typically emerges when the event date is proximate and no material scheduling uncertainty remains visible in public information.

The B League's fixture schedule has historically demonstrated high reliability in execution, with postponements rare outside of severe weather or public health emergencies. Comparable markets on Japanese professional basketball fixtures have shown that once games enter the final week before tip-off without official postponement notices, the probability of completion approaches the levels currently observed here. The settlement window extends to 9 May, providing a five-day buffer beyond the scheduled date to accommodate any last-minute rescheduling.

Traders should monitor official B League communications for any injury announcements affecting key players, venue access issues, or scheduling changes. Recent B League seasons have maintained consistent fixture completion rates, though international travel disruptions or local weather patterns in the Aichi and Saitama prefectures could theoretically trigger delays. The 2:05 AM ET timing reflects the Japan time zone conversion and represents a standard regular-season fixture window. No recent news indicates complications for either franchise's participation.

Resolution source

This market settles from the official outcome published at https://www.bleague.jp/en/. A proposer submits the final result to the UMA optimistic oracle on Polygon; the two-hour dispute window closes and payouts clear in USDC.

How to trade this market step by step

The mechanics for trading "SeaHorses Mikawa vs. Koshigaya Alphas" are the same as any other PolyGram sporting event contract. Each YES share resolves to $1 if the event happens, or $0 if it doesn't. The current price between 0¢ and 100¢ is the market's probability estimate, set live by the order book.

1. Sign in on polygram.ink with your email — no full KYC under $1,500 lifetime trading volume.
2. Deposit USDC on Polygon (lowest fees, ~$0.01 per transaction) or Ethereum. Funds credit after 12 confirmations.
3. Pick a side. Buy YES if you believe the event will happen; buy NO if you think it won't. The current YES price reflects the market's collective probability.
4. Size your position. If you stake 100 USDC at 100% YES, you'll receive shares that pay $100 if YES resolves true — a 0% gross return. If NO resolves, your shares are worth $0.
5. Set risk controls (optional). Stop-loss, take-profit, and limit-order types all supported. Use the trade ticket's slippage box to cap your maximum entry price.
6. Wait for resolution. When the event resolves on-chain via the UMA optimistic oracle, the winning side settles to 100¢ automatically and USDC hits your balance within seconds. Withdrawable to any wallet you control.

How active is this market?

$4K in lifetime turnover and $0 of resting liquidity puts this market in the below the median by volume for sports contracts on PolyGram. Order-book depth is thin — large orders may need to be split across the book or executed as limit orders.

The market has been open for under a month — fresh enough that information asymmetry remains a real factor.

Higher-volume markets tend to have tighter spreads and faster price discovery — meaning the displayed YES/NO percentages are more likely to reflect the true crowd-implied probability rather than a single trader's directional view.

Key terms

YES / NO share

A binary outcome token that pays $1.00 if the underlying claim resolves true (YES) or false (NO), and $0 otherwise. The market price between 0¢ and 100¢ is the implied probability.

CLOB

Central limit order book. The matching engine that pairs YES buyers with NO buyers (effectively the same trade). Polymarket's CLOB on Polygon executes trades on-chain via the conditional-tokens framework.

Liquidity

USDC capital sitting in resting limit orders inside the order book. Deeper liquidity means smaller slippage on large trades and a tighter bid-ask spread.

UMA optimistic oracle

The on-chain dispute system that settles each Polymarket market. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution.

Slippage

The difference between the displayed mid-price and your fill price. Affects market orders most; limit orders avoid slippage but may take time to fill.

Conditional token

ERC-1155 outcome share issued by Gnosis Conditional Tokens on Polygon. The token type that resolves to $1.00 or $0.00 at settlement.

See the full prediction-market glossary →

Frequently asked questions

Risk and regulatory note

Prediction-market positions can lose 100% of staked capital. Outcomes are uncertain by definition — historical accuracy of crowd-implied probabilities is high in aggregate but not for any single market. PolyGram does not provide investment advice. Trade only with capital you can afford to lose.

Regulatory status varies by jurisdiction. Germany, the United States, and most EU countries treat Polymarket-style event contracts under one of three frameworks: financial derivative, gambling product, or unregulated novel asset. Consult local counsel before trading.

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