Claude Sonnet-4.5 & Haiku 4.5 In-Depth Review | Performance, Usage, and Comparison of Anthropic's Latest AI Models

The Latest Models in the Claude Series Arrive

Developed by Anthropic, a company that emphasizes AI safety and ethics, the "Claude" series has garnered attention for its advanced conversational ability and reliability. The "Claude Sonnet-4.5" and "Claude Haiku 4.5," released from the Claude series in 2025, each possess distinct strengths and are designed to meet the diversifying needs of users. This article focuses on and details Claude Sonnet-4.5 and Haiku 4.5. We will clarify how they expand business and creative activities, based on the philosophy of "Constitutional AI" advocated by Anthropic.

Claude Sonnet-4.5: AI Where Natural Japanese Generation and Advanced Analysis Converge

What is Claude Sonnet-4.5?

Claude Sonnet-4.5 is an AI model developed by Anthropic that combines advanced conversational ability and analytical capabilities. It excels particularly in natural and accurate Japanese language generation, has a high comprehension of complex instructions, and is adept at reading and summarizing long texts and extracting deep insights from them. Based on the philosophy of "Constitutional AI" prioritized by Anthropic, it incorporates safety and ethical considerations, allowing it to be utilized as a highly reliable AI assistant.

Characteristics of Claude Sonnet-4.5

• Natural and Accurate Japanese Generation
  It deeply understands the nuances of the Japanese language and generates natural, easy-to-read text. It can handle diverse Japanese expressions, from business documents to creative writing.
• Advanced Conversational Ability and Comprehension of Complex Instructions
  It accurately grasps the user's intent and engages in natural, precise dialogue consistent with the context. It has a high capability to understand and execute complex instructions involving multiple conditions or constraints.
• Strength in Long Text Reading, Summarization, and Analysis
  It efficiently processes large volumes of text data, accurately extracts key points, and provides logical analysis results. It demonstrates its capability in report creation and information gathering.
• Safety Based on Ethical Consideration and "Constitutional AI"
  "Constitutional AI," which embeds the ethical use of AI as a guideline, reduces the risk of generating harmful or inappropriate responses, enabling safe and reliable usage.

Ideal Uses for Claude Sonnet-4.5

Claude Sonnet-4.5 is optimal for the following scenarios that require advanced intelligence and analytical power:

• Detailed Information Analysis and Report Creation
  Creates detailed analysis reports, such as market trends, competitor analysis, or academic papers, based on provided data and documents. It is ideal for reports requiring accurate Japanese expression.
• Brainstorming / Bouncing Ideas (Deep Discussion)
  Supports idea proposals from various perspectives, deep discussions on existing ideas, and comparison of merits and drawbacks during new project planning or strategy formulation.
• Blog Post, SNS Post, and Web Content Creation
  Suitable for creating content that combines a logical structure to aid reader comprehension with natural and engaging Japanese expression.
• Programming Code Review and Debugging Assistance
  Supports the development process, including code quality checks, identifying potential bugs, and suggesting improvements.

Specific Use Cases for Claude Sonnet-4.5

Example 1: Comparison and Review of Project Plans

"Analyze the image of the whiteboard taken during this brainstorming meeting, and summarize the key ideas discussed, decisions made, and future tasks as structured meeting minutes."

Example 2: Creating Service Descriptions for a Website

"(Attach images of three design proposals) Compare the images of these product design proposals, analyze their respective merits, drawbacks, and appeal to the target customer in detail, and propose the most recommended option with justification."

Example 3: Code Quality Review

"Review the following Python code and suggest areas for improvement, security concerns, and performance optimization." Contributes to improving development quality and the early detection of potential risks.

Claude Haiku 4.5: Lightweight High-Speed Model Excelling in Japanese Comprehension

What is Claude Haiku 4.5?

Claude Haiku 4.5 is an AI model offered by Anthropic, characterized by extremely fast response speed and lightweight design. It prioritizes simplicity and accessibility over complexity while maintaining accuracy in Japanese comprehension, achieving efficiency in daily operations. It instantly handles minor daily tasks, dramatically improving operational efficiency.

Key Characteristics of Claude Haiku 4.5

• Extremely Fast Response Speed
  Generates responses to user instructions in a very short time. It is suitable for applications requiring real-time performance or rapid-paced dialogue.
• Maintains Japanese Comprehension Accuracy Despite Lightweight Model Size
  Because the model is lightweight, it requires less computational resources to operate and can be easily used across various devices and platforms. Simultaneously, it possesses the ability to accurately understand the subtle nuances of the Japanese language.
• Simple and Intuitive
  User Experience Users can easily reap the benefits of the AI without complex settings or advanced specialized knowledge. It lowers the barrier to introducing AI into daily operations.

Ideal Uses for Claude Haiku 4.5 Claude

Haiku 4.5 is optimal for the following uses where speed and convenience are prioritized:

• Simple Q&A and Information Retrieval
  Can be used for quick information acquisition, such as resolving everyday questions or verifying specific facts. It accurately responds to natural language questions in Japanese.
• Idea Generation for SNS Posts and Short Text Creation
  Useful for quickly generating multiple ideas or creating concise and attractive Japanese posts suitable for social media.
• Email Drafting Assistance and Proofreading
  Supports the efficiency of communication tasks, such as drafting email bodies, checking for typos, and improving expressions to sound more natural in Japanese.
• Concise Description of Uploaded Images
  Quickly grasps the content of an image and generates a concise and accurate Japanese description.
• Quick Summary of Meeting Minutes
  Can be used to quickly extract and summarize decisions and responsible parties from meeting notes or records, maintaining accuracy in Japanese expression.

Specific Use Cases for Claude Haiku 4.5

Example 1: Describing an Uploaded Image

"Create a concise description of the visual features of this uploaded product image, intended for communicating to customers."

Example 2: Extracting Key Points from Meeting Minutes

"From the following meeting minutes (text), extract the decisions made and the responsible parties, and list them using bullet points."

Example 3: Short Catchphrase Proposal

"Propose three short catchphrases about 'the benefits of remote work,' suitable for an SNS post."

Claude Sonnet-4.5 vs Haiku 4.5: Model Comparison and Strategic

Usage Model Comparison Chart

Key Points for Model Selection: What Criteria to Use

👉 If High-Quality Analysis or Deep Thinking is Required: Claude Sonnet-4.5

For tasks requiring high-quality output, Sonnet-4.5's advanced processing power and Japanese generation accuracy provide significant value. It is optimal in situations where the AI is needed as a "thinking partner," such as analyzing complex charts/graphs, creating detailed reports, and structuring logical documents.

👉 If Prioritizing Efficiency and Speed in Daily Tasks: Claude Haiku 4.5

For optimizing routine tasks and requiring fast responses, Haiku 4.5 offers excellent cost performance while maintaining accuracy in Japanese comprehension. It is highly effective when you want to quickly process daily tasks and boost productivity.

Summary: Expanding the Scope of AI Utilization with the Claude Series

This article provided a detailed explanation of the features of Anthropic's latest AI models, Claude Sonnet-4.5 and Claude Haiku 4.5, by covering their respective characteristics, ideal applications, specific use cases, and a comparison between the two models. Both models are designed based on the "Constitutional AI" approach advocated by Anthropic, ensuring safe and ethical AI usage, so users can utilize the AI's capabilities with confidence. Especially in business scenarios requiring natural and accurate Japanese ability, the reliability and conversational capability of the Claude series serve as a powerful asset. Utilizing Sonnet-4.5 for deep analysis and creation, and Haiku 4.5 for efficiently handling daily tasks—this strategic differentiation is the key to maximizing the effectiveness of AI utilization.