## 1 Introduction  
Labeling the origin of food ingredients is an important factor when consumers assess the quality and safety of a product. In Japan, labeling the origin of ingredients in processed foods has been mandatory since April 2022 [1], and interest in the accuracy of this labeling has been increasing. This trend is not limited to Japan but is observed globally. For example, labeling the origin of food is mandatory under European Union Law [2] and in the US under the Code of Federal Regulations [3]. The introduction of such systems has enabled consumers to obtain transparent information, and the labeling of origin contributes to improving the reliability of food. In contrast, the problem of food fraud remains a significant issue. People try to profit by fraudulently using the names of production areas and varieties with high market value. Fraudulent acts, such as false labeling of the origin of high-value products, pose a risk to consumer trust and safety. Therefore, a reliable method is required to verify the origin of food and to support accurate labeling. The flavor and ingredients of kelp are different depending on the origin and variety, and there are large differences in distribution prices. Identifying the origin and variety of kelp is important for food quality assurance, distribution management, and regional brand protection. DNA and chemical analyses based on the soil composition of the production area have been used to identify the origin of kelp using physicochemical tests. [PERSON] et al. [4] have performed inorganic element analysis of kelp produced in Japan and China using inductively coupled plasma mass spectrometry (ICP-MS) and developed a method for determining the origin of kelp using inorganic elements as indicators. [PERSON] et al. [5] have also demonstrated the effectiveness of elemental analysis of wakame seaweed using ICP-MS for identifying the origin of kelp. [PERSON] et al. [6] have developed a DNA extraction method with high amplification by polymerase chain reaction, extracted mitochondrial DNA from 10 types of kelp, and performed genetic analysis. In this study, six types of kelp have been identified; however, almost no difference has been found in base sequences between Ma-kombu (_Lonicera japonica_) and its varieties Rishiri-kombu (_Laminaria ochotensis_) and Rausu-kombu (_L. ochotensis_), indicating that further detailed studies are necessary. Ma-kombu and its varieties, Rausu-kombu and Rishiri-kombu, have a low degree of speciation, and the base sequences of rDNA internal transcribed spacer 1 (ITS-1) and RuBisco spacer, which are effective in detecting species differences in many brown algae, are completely identical [7]. Various studies have been conducted to identify the geographical origins of food, such as coffee beans, fruit spirits, and Chinese red wine [8; 9; 10; 11]. The methods used to distinguish the origins include terahertz (THz) spectroscopy, Raman spectroscopy, ultraviolet-visible (UV-VIS) spectroscopy, and NIR spectroscopy. Fluorescence spectroscopy is a method for measuring food characteristics by using the properties of substances to absorb light at certain wavelengths and emit light at different wavelengths. [PERSON] et al. [12] have demonstrated the possibility of using excitation-emission matrix fluorescence spectroscopy combined with chemometrics to distinguish the geographical origins of rice from other varieties. [PERSON] et al. [13] have identified the variety and geographical origin of Italian olive oil. [PERSON] et al. [14] have proposed a method for identifying the botanical origin of Swiss honey. [PERSON] et al. [15] have detected insects infesting wheat grains using front-face fluorescence and UV-VIS spectroscopy. The effectiveness of fluorescence spectroscopy has been confirmed for a wide variety of foods, including rice, olive oil, honey, and wheat. A lot of information can be obtained more simply and efficiently by fluorescence spectroscopy than conventional physicochemical analysis.