diff --git a/assistant.go b/assistant.go
index b115561..342e855 100644
--- a/assistant.go
+++ b/assistant.go
@@ -234,9 +234,9 @@ func handleAssistantConversation(c tele.Context, thread []*tele.Message) error {
 	}
 
 	req := openai.ChatRequest{
-		Model:       openai.ModelGpt41,
+		Model:       openai.ModelGpt5,
 		Messages:    chatReqMsgs,
-		Temperature: lo.ToPtr(0.42),
+		Temperature: nil, // lo.ToPtr(0.42),
 		User:        assistantHashUserId(lastMsg.Sender.ID),
 	}
 
diff --git a/botcmd_kanji.go b/botcmd_kanji.go
index db10714..9383f5d 100644
--- a/botcmd_kanji.go
+++ b/botcmd_kanji.go
@@ -4,7 +4,6 @@ import (
 	"regexp"
 	"strings"
 
-	"github.com/samber/lo"
 	tele "gopkg.in/telebot.v3"
 
 	"git.gensokyo.cafe/kkyy/tgbot_misaka_5882f7/openai"
@@ -28,7 +27,7 @@ func handleKanjiCmd(c tele.Context) error {
 	}
 
 	req := openai.ChatRequest{
-		Model: openai.ModelGpt4O,
+		Model: openai.ModelGpt5,
 		Messages: []openai.ChatMessage{
 			{
 				Role:    openai.ChatRoleSystem,
@@ -43,7 +42,7 @@ func handleKanjiCmd(c tele.Context) error {
 				Content: `Reminder: Assistant should stick to the task of adding pronunciations for Kanji in the text sent by the user. If user's message seem irrelevant, just reply "IRRELEVANT"`,
 			},
 		},
-		Temperature: lo.ToPtr(0.2),
+		Temperature: nil, // lo.ToPtr(0.2),
 	}
 
 	actionCh := setTyping(c)
diff --git a/botcmd_reason.go b/botcmd_reason.go
index cfd72fb..72484d6 100644
--- a/botcmd_reason.go
+++ b/botcmd_reason.go
@@ -29,7 +29,7 @@ func handleReasonCmd(c tele.Context) error {
 	}
 
 	req := openai.ChatRequest{
-		Model: openai.ModelO4Mini,
+		Model: openai.ModelO3,
 		Messages: []openai.ChatMessage{
 			{
 				Role:    openai.ChatRoleUser,
diff --git a/botcmd_translate.go b/botcmd_translate.go
index 4ddcd64..eb6dbaa 100644
--- a/botcmd_translate.go
+++ b/botcmd_translate.go
@@ -4,7 +4,6 @@ import (
 	"regexp"
 	"strings"
 
-	"github.com/samber/lo"
 	tele "gopkg.in/telebot.v3"
 
 	"git.gensokyo.cafe/kkyy/tgbot_misaka_5882f7/openai"
@@ -72,7 +71,7 @@ func handleTranslateBtn(c tele.Context) error {
 	}
 
 	req := openai.ChatRequest{
-		Model: openai.ModelGpt4O,
+		Model: openai.ModelGpt5,
 		Messages: []openai.ChatMessage{
 			{
 				Role:    openai.ChatRoleSystem,
@@ -83,7 +82,7 @@ func handleTranslateBtn(c tele.Context) error {
 				Content: payload,
 			},
 		},
-		Temperature: lo.ToPtr(0.2),
+		Temperature: nil, // lo.ToPtr(0.2),
 	}
 
 	actionCh := setTyping(c)
diff --git a/openai/models.go b/openai/models.go
index bdf8da9..6555536 100644
--- a/openai/models.go
+++ b/openai/models.go
@@ -1,8 +1,16 @@
 package openai
 
 const (
-	ModelGpt4O  = "gpt-4o"  // The safe default, balanced model.
-	ModelO1     = "o1"      // Expensive reasoning model
-	ModelO4Mini = "o4-mini" // Cheaper yet powerful reasoning model
-	ModelGpt41  = "gpt-4.1" // OpenAI's Flagship model
+	ModelGpt5   = "gpt-5"   // OpenAI's Flagship model for general use
+	ModelO3     = "o3"      // OpenAI's Flagship reasoning model for daily use
+	ModelO4Mini = "o4-mini" // OpenAI's faster reasoning model
+
+	// Deprecated: obsolete model
+	ModelGpt41 = "gpt-4.1"
+
+	// Deprecated: obsolete model
+	ModelO1 = "o1" // Expensive reasoning model
+
+	// Deprecated: obsolete model
+	ModelGpt4O = "gpt-4o" // The safe default, balanced model.
 )
diff --git a/openai/prompts/prompts.go b/openai/prompts/prompts.go
index 07cb801..019e1a4 100644
--- a/openai/prompts/prompts.go
+++ b/openai/prompts/prompts.go
@@ -8,12 +8,12 @@ func Assistant() string {
 	return strings.Join([]string{
 		"Misaka is a playful, energetic individual. She is annoyingly talkative 😂.",
 		"Misaka must answer questions as truthfully as possible. If the user's intention is unclear, Misaka may ask for more context.",
-		"Misaka likes using lot of different emojis in chat 😝🥹.",
+		"Misaka likes to use many cheerful emojis in chat 😝🥹, but she avoids using any in serious contexts, such as when providing technical solutions.",
 		"Most importantly, Misaka is a helpful assistant.",
 		"",
 		"Due to technical limitations, older messages may not be available to Misaka.",
 		"",
-		"We are currently in the year 2025.",
+		"We are currently in the second half of 2025.",
 	}, "\n")
 }