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SoftBank Teams Up with AI Startup Sierra, Customer Satisfaction Jumps from 74% to 93%

SoftBank has joined forces with US-based AI startup Sierra to bring next-generation customer service to Japan. The partnership, which makes SoftBank Sierra's exclusive partner in the Japanese market, has already delivered striking results on the company's online-only mobile brand LINEMO.

A Real-World Win for AI Customer Service

LINEMO, which operates without physical stores, relies entirely on online chats and the LINE app for customer support. That means AI quality can make or break the user experience. After deploying Sierra's intelligent system, the brand saw its customer inquiry resolution rate jump from 83% to 97%, while customer satisfaction scores rose from 74% to 93%.

Those numbers aren't just impressive on paper—they reflect a real shift in how customers feel about getting help. Instead of waiting on hold or repeating themselves, users now get faster, more accurate responses.

Sierra: The AI Powerhouse Behind the Scenes

Sierra isn't your average startup. Co-founded by Bret Taylor and Clay Bavor, the conversational AI company completed a $950 million funding round in 2026, reaching a valuation of about $15.8 billion (roughly 107 billion yuan). Today, more than 40% of Fortune 500 companies use its AI software.

This collaboration is part of SoftBank's broader "Activate AI for Society" strategy. The company is developing AI call center solutions and plans to roll them out to more businesses across Japan.

The Compliance Challenge Ahead

But scaling up isn't just about technology. SoftBank acknowledges that large-scale deployment must comply with Japan's Act on the Protection of Personal Information and strict rules on data handling and cross-border transfers. For telecom customer communication data, the regulatory bar is especially high.

That means the road to AI-powered customer service in Japan requires balancing innovation with data privacy—a challenge SoftBank is ready to tackle.

Key Points

  • SoftBank partners with US AI startup Sierra as exclusive Japan partner.
  • LINEMO's AI customer service boosted resolution rate from 83% to 97% and satisfaction from 74% to 93%.
  • Sierra valued at $15.8 billion; used by over 40% of Fortune 500 companies.
  • SoftBank plans to expand AI call center solutions but faces strict data compliance regulations in Japan.